whats the dif between a ho72 and a ho52? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

crew70 · 06-15-2002, 11:43 PM

I have a 70 3/4 ton 4x4. what rear end would I have and how would I tell? I just put all new seals and brakes in it and i orderd then for a ho52 and they all fit.i dont know if the ho72 is thatdif or not.I know it is one of the two. I have had several 3/4 ton 4x4s and the rear ends all look the same. my rear end is a posi. I was tould that is rare. isit?

junkyardjohn · 06-16-2002, 12:31 AM

NOT TO SURE HMMMM- LETS SEE HERE, THE DIFFERANCE BETWEEN AN HO52 AN A HO72 HMMMMMM I WOULD THINK IT WOULD BE ABOUT 20 HOs. LOL

**COBALT** · 06-16-2002, 03:57 AM

This was an interesting debate not too long ago. I have what looks like an HO72 under my '69 3/4 ton C20 truck (10 bolt Corp. GM axle with Eaton carrier). It came stock with spiders (no eaton posi) and 4.10 gears. I have the same under my '69 3/4 ton Custom 20. Both have coil suspension. Both are 8 lug axles.

According to Fast68Chevy HO72's were only under 1 tons, and were only leaf sprung. Therefore, I must be mistaken and have HO52 axles. Problem is the codes on the housing tell me HO72. My GVW is also 7500 lbs, which is consistent with HO72 axles. Therefore, I had to conclude that the whole 1 ton theory is out the window.

Bottom line: check the codes. Know your GVW, and know your gear ratio. That's the only way to know what it is.

crew70 · 06-16-2002, 09:42 AM

where on the housing would i find the codes?

Longhorn Man · 06-16-2002, 10:07 AM

Quote:

Originally posted by crew70
where on the housing would I find the codes?

Yeah, ditto for me, it never mattered to me, but now that I have the one ton out there...

Mike C · 06-16-2002, 10:49 AM

Check your vin plate on the door. It shows a max capacity REAR axle weight (Not total GVWR) and an as equipped rear weight. The as equipped rate is obviously what your truck is outfitted with from the factory. The max for the 3/4 ton platform is 5500 #'s, which would have had a Dana 60. If 5200# or less, if could have been a 60 or the HO52. (5200# rated) They are the same housing I believe, but the 52 has a 2 pinion diff and the 72 and 4 pinion, I THINK>

crew70 · 06-16-2002, 01:09 PM

I have a 5200# grose rear axle on the tag.I know the dif between a dana and an eaton , just not a 52 and 72.I have never seen a dana in a 3/4 ton 4x4 in the 67-72 vintage that was factory. am I wrong ?

hay Idea? does the 52 in ho52 stand for 5200# and
72 in ho72 stand for 7200#?

Mike C · 06-16-2002, 05:33 PM

I believe they were available in 4x4. Hopefully someone who has one can reply. Of the (3) 3/4 trucks and (1) 3/4 Sub that I have had/have, only the sub had the HO52 axle, all the others were leaf spring 60's. 3.54, 3.73 and a yet to be determined axle in the last parts truck. Tag was gone off the cover.

HeavyK20 · 06-16-2002, 11:43 PM

Quote:

I have never seen a dana in a 3/4 ton 4x4 in the 67-72 vintage that was factory. am I wrong ?

I have a 71 GMC 3/4 ton 4x4 rolling chassis with a Dana 60 Rear.

PushinPebbles · 06-17-2002, 12:33 AM

Junkyard John............ROFLMAO

*Fast68Chevy* · 06-17-2002, 12:45 AM

Mike's right, 4 pinion in the 72's and all were leaf sprung, the 52's were 3/4 ton only and were 2 pinion,
external differences dont exist, only internal ones,
the only way that new69 could have a 72 model under his with coils is if someone did some welding to convert it to coils useage, because all 72's were leaf.

Patrick Sullivan · 06-17-2002, 01:15 AM

Now I'm really confused, the codes on my axle tell me it's an HO72 as well, and it's coil sprung. Don't know what the door plate says, as my truck is sitting in a tranny shop right now. I'll look when I get it back..

Either we have a mad chevy owner converting HO72's to coil springs, or they weren't all leaf..

Big69C20 Toy · 06-17-2002, 05:43 AM

Yeah i've got an HO72 according to all the parts i've gotten for it. requires one monster of a pinion seal and my truck is coil sprung, who knows what all them crazy gm'ers were doin back then..

**JIMs70GMC** · 06-17-2002, 06:53 AM

I have a 70 GMC 3/4 ton 4x4 that has a dana 60 w/ powr-loc limited slip. All original.

**breeh** · 06-17-2002, 10:57 AM

My '72 3/4 4x4 has a factory Dana 60 as well...

**Yukon Jack** · 06-17-2002, 11:07 AM

The door plate on my 69 K20 says Maximum GVW Rating 7500. My glove box says nothing about the rear axle and I have never searched my axle for codes.

Mike C · 06-17-2002, 02:20 PM

Mark, The door plate will show max GVWR for the platform (7500) AND for your truck as equipped (6200,6600,7000,7500 are variations on the 4 3/4 ton trucks I have had) It will also show max weight front and max weight rear both for the platform (5500#) and your truck. (5200# in the case of my 70 3/4 big block Dana 60 3.54 gears and leaf springs.) Check out the door plate for all of the different numbers and report back if you would. Brakes, springs, shocks, tires, trans, and gear ratio can all have an effect on what GM rated the truck at.
mc

**Yukon Jack** · 06-17-2002, 03:02 PM

My metal plate only shows the Maximum GVW Rating, no other ratings. It also shows the VIN and there is metal plate below it that shows something to the effect of this chassis-cab conforms to all federal standards. I can't find any other plates concerning weight ratings. Is that odd?

*Fast68Chevy* · 06-17-2002, 03:29 PM

well h052 and ho72 parts are same cept for pinions, so parts interchange is same between them for 95% of the things

dana60 rasting is 5500 lbs, 300 more than a h052, ho52 is 3/4 ton axle and h072 is std 1 ton axle and ho110 is the optional 5 lug 11,000lb axle with parkiing drum on rear of tranny, bet none of you hahve seen an 11,000lb optional HD C30 yet 67-72, hehe

good luck finding one, i think only one member has one or saw one- MrSpeed

good luck

Rod · 06-17-2002, 08:58 PM

Seen a few around here.... A couple guys are looking for rear drums for those 11,000 pond rears here too... those are harder to find than my 72 dually rear drums.

crew70 · 06-17-2002, 09:38 PM

Ok now you really got me confused!!! no really I think I finally got it. ? except for the 2 pinon and 4 pinon?? I have had mine apart but there was only one pinon gear?? help me out here could ya?

Mike C · 06-17-2002, 10:31 PM

Sorry for the confusion Crews. Yes, there is only one ring and pinion gear, but in the style differential unit, they refer to the spider gears on the cross pins as pinion gears, and in the 52 there is two pins and two gears and on the 72 there are 4 pins and 4 spiders. Try to find a mag ad that shows what a Detroit Locker for a 14 bolt looks like, and you'll see the 4 pins sticking out.

Yukon Jack, I'll get a shot of my data plate as soon as I can and post it to show what mine is like. Maybe they changed in 70? Maybe it depends on what plant the truck was assembled at? I'm not sure.

Duallie · 06-18-2002, 02:48 AM

An HO52 (5200 lbs) has 2 spider gears.
An HO72 (7200 lbs) has 4 spiders.
A Detroit Locker doesn't have any spiders. I am not sure what rating to apply to a Locker-equipped Eaton. I would probably use the spring rating.
Crew70: Your Eaton has a Detroit Locker. PosiTraction differentials use clutches to slip; lockers use meshing gears when they lock.

06-15-2002, 11:43 PM	#1
crew70 Registered User Join Date: Jan 2002 Location: shafer,mn,usa Posts: 316	whats the dif between a ho72 and a ho52? I have a 70 3/4 ton 4x4. what rear end would I have and how would I tell? I just put all new seals and brakes in it and i orderd then for a ho52 and they all fit.i dont know if the ho72 is thatdif or not.I know it is one of the two. I have had several 3/4 ton 4x4s and the rear ends all look the same. my rear end is a posi. I was tould that is rare. isit?

06-16-2002, 12:31 AM	#2
junkyardjohn Registered User Join Date: Aug 2001 Location: SOMERSET KY. Posts: 6,427	NOT TO SURE HMMMM- LETS SEE HERE, THE DIFFERANCE BETWEEN AN HO52 AN A HO72 HMMMMMM I WOULD THINK IT WOULD BE ABOUT 20 HOs. LOL __________________ junkyardjohn 69 1 TON TOW TRUCK // 84 4WD CUCV BLAZER// 85 1 TON 4WD STAKE TRUCK// 86 M1031 5/4 TON 4WD CUCV// ALOT OF OLD TRUCKS FOR ONE OLD MAN TO DRIVE. THERES ROOM FOR ALL OF GODS CREATURES RIGHT NEXT TO MY MASHED POTATOES// LIFE MEMBER OF P.E.T.A (PEOPLE EATING TASTY ANIMALS) DON'T RENT U-HAUL ALWAYS TELL THE TRUTH IT WILL AMAZE PART OF THE PEOPLE & ASTONISH THE REST

06-16-2002, 03:57 AM	#3
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	This was an interesting debate not too long ago. I have what looks like an HO72 under my '69 3/4 ton C20 truck (10 bolt Corp. GM axle with Eaton carrier). It came stock with spiders (no eaton posi) and 4.10 gears. I have the same under my '69 3/4 ton Custom 20. Both have coil suspension. Both are 8 lug axles. According to Fast68Chevy HO72's were only under 1 tons, and were only leaf sprung. Therefore, I must be mistaken and have HO52 axles. Problem is the codes on the housing tell me HO72. My GVW is also 7500 lbs, which is consistent with HO72 axles. Therefore, I had to conclude that the whole 1 ton theory is out the window. Bottom line: check the codes. Know your GVW, and know your gear ratio. That's the only way to know what it is. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

06-16-2002, 10:49 AM	#6
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,709	Check your vin plate on the door. It shows a max capacity REAR axle weight (Not total GVWR) and an as equipped rear weight. The as equipped rate is obviously what your truck is outfitted with from the factory. The max for the 3/4 ton platform is 5500 #'s, which would have had a Dana 60. If 5200# or less, if could have been a 60 or the HO52. (5200# rated) They are the same housing I believe, but the 52 has a 2 pinion diff and the 72 and 4 pinion, I THINK> __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

06-16-2002, 05:33 PM	#8
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,709	I believe they were available in 4x4. Hopefully someone who has one can reply. Of the (3) 3/4 trucks and (1) 3/4 Sub that I have had/have, only the sub had the HO52 axle, all the others were leaf spring 60's. 3.54, 3.73 and a yet to be determined axle in the last parts truck. Tag was gone off the cover. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

06-16-2002, 09:42 AM	#4
crew70 Registered User Join Date: Jan 2002 Location: shafer,mn,usa Posts: 316	where on the housing would i find the codes?

06-16-2002, 01:09 PM	#7
crew70 Registered User Join Date: Jan 2002 Location: shafer,mn,usa Posts: 316	I have a 5200# grose rear axle on the tag.I know the dif between a dana and an eaton , just not a 52 and 72.I have never seen a dana in a 3/4 ton 4x4 in the 67-72 vintage that was factory. am I wrong ? hay Idea? does the 52 in ho52 stand for 5200# and 72 in ho72 stand for 7200#?

06-17-2002, 12:33 AM	#10
PushinPebbles My dad's 68 Join Date: May 2002 Location: VA Posts: 444	Junkyard John............ROFLMAO __________________ Jack M. 67 C-10 SWB 355 built T-350 tranny hurst shifter 17x8in KMC's on michelins, clear tails and back up lights slammedUPDATE i have decided on my bag setup and will post further info when i recieve all the parts **************************** 88 1/2 ton suburban 4x4 350/700R-4having a 9 in lift w/ 38 in tires 4 12 inch Lightning Audios *************************** 87 silverado 3/4ton jacked up 10-12 inches black and rubberized bed coating 35 in michelans ************************** Dad's truck 68 C-10 stepside, 468 BB, tubbed, weld wheels, Nason black,lots more **************************** grand dads truck 68 C-10 stepside fuel inj. 350/700R-4soon in audi silver **************************** 84 toyota pickup 22R 5 speed 2WD slammed, shaved and all the body lines filled w/ buickGN scoop,bout to be sprayed in 2003 mustang green metallic w/ silver flames **************************** S/N=BIGGYTYME@aol.com (hydros) "No fat chics, truck will scrape"

06-17-2002, 12:45 AM	#11
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	Mike's right, 4 pinion in the 72's and all were leaf sprung, the 52's were 3/4 ton only and were 2 pinion, external differences dont exist, only internal ones, the only way that new69 could have a 72 model under his with coils is if someone did some welding to convert it to coils useage, because all 72's were leaf.

06-17-2002, 01:15 AM	#12
Patrick Sullivan Transcendental Trucker Join Date: Dec 2001 Location: Rockaway Beach, OR Posts: 374	Now I'm really confused, the codes on my axle tell me it's an HO72 as well, and it's coil sprung. Don't know what the door plate says, as my truck is sitting in a tranny shop right now. I'll look when I get it back.. Either we have a mad chevy owner converting HO72's to coil springs, or they weren't all leaf.. __________________ Patrick Sullivan \| sullivan@oregoncoast.com Rockaway Beach, Oregon 1972 Chevy Cheyenne C-20 1998 Dodge Dakota 4x4 So, fill to me the parting glass And drink a health whate'er befalls... Then gently rise and softly call Goodnight and joy be to you all!

06-17-2002, 05:43 AM	#13
Big69C20 Toy Livin' it up. Join Date: Nov 2001 Location: Richland, MI Posts: 2,212	Yeah i've got an HO72 according to all the parts i've gotten for it. requires one monster of a pinion seal and my truck is coil sprung, who knows what all them crazy gm'ers were doin back then.. __________________ -Greg; Sold the 69 C20. It's off to a better home with more love! Now onto the 86 CUCV M1009; K5 blazer with 6.2L diesel, corp 10 bolt axles, Detroit locker in the rear, trutrac front, 3.73 gears, 35" tires.

06-17-2002, 06:53 AM	#14
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	dana 60 I have a 70 GMC 3/4 ton 4x4 that has a dana 60 w/ powr-loc limited slip. All original. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

06-17-2002, 10:57 AM	#15
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	My '72 3/4 4x4 has a factory Dana 60 as well... __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

06-17-2002, 11:07 AM	#16
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,683	The door plate on my 69 K20 says Maximum GVW Rating 7500. My glove box says nothing about the rear axle and I have never searched my axle for codes. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

06-17-2002, 02:20 PM	#17
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,709	Mark, The door plate will show max GVWR for the platform (7500) AND for your truck as equipped (6200,6600,7000,7500 are variations on the 4 3/4 ton trucks I have had) It will also show max weight front and max weight rear both for the platform (5500#) and your truck. (5200# in the case of my 70 3/4 big block Dana 60 3.54 gears and leaf springs.) Check out the door plate for all of the different numbers and report back if you would. Brakes, springs, shocks, tires, trans, and gear ratio can all have an effect on what GM rated the truck at. mc __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax



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06-17-2002, 03:02 PM	#18
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,683	My metal plate only shows the Maximum GVW Rating, no other ratings. It also shows the VIN and there is metal plate below it that shows something to the effect of this chassis-cab conforms to all federal standards. I can't find any other plates concerning weight ratings. Is that odd? __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

06-17-2002, 03:29 PM	#19
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	well h052 and ho72 parts are same cept for pinions, so parts interchange is same between them for 95% of the things dana60 rasting is 5500 lbs, 300 more than a h052, ho52 is 3/4 ton axle and h072 is std 1 ton axle and ho110 is the optional 5 lug 11,000lb axle with parkiing drum on rear of tranny, bet none of you hahve seen an 11,000lb optional HD C30 yet 67-72, hehe good luck finding one, i think only one member has one or saw one- MrSpeed good luck

06-17-2002, 08:58 PM	#20
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	Seen a few around here.... A couple guys are looking for rear drums for those 11,000 pond rears here too... those are harder to find than my 72 dually rear drums. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

06-17-2002, 09:38 PM	#21
crew70 Registered User Join Date: Jan 2002 Location: shafer,mn,usa Posts: 316	Ok now you really got me confused!!! no really I think I finally got it. ? except for the 2 pinon and 4 pinon?? I have had mine apart but there was only one pinon gear?? help me out here could ya?

06-17-2002, 10:31 PM	#22
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,709	Sorry for the confusion Crews. Yes, there is only one ring and pinion gear, but in the style differential unit, they refer to the spider gears on the cross pins as pinion gears, and in the 52 there is two pins and two gears and on the 72 there are 4 pins and 4 spiders. Try to find a mag ad that shows what a Detroit Locker for a 14 bolt looks like, and you'll see the 4 pins sticking out. Yukon Jack, I'll get a shot of my data plate as soon as I can and post it to show what mine is like. Maybe they changed in 70? Maybe it depends on what plant the truck was assembled at? I'm not sure. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

06-18-2002, 02:48 AM	#23
Duallie Registered User Join Date: Feb 2001 Location: Nikiski, Alaska Posts: 477	An HO52 (5200 lbs) has 2 spider gears. An HO72 (7200 lbs) has 4 spiders. A Detroit Locker doesn't have any spiders. I am not sure what rating to apply to a Locker-equipped Eaton. I would probably use the spring rating. Crew70: Your Eaton has a Detroit Locker. PosiTraction differentials use clutches to slip; lockers use meshing gears when they lock. __________________ Just as if I knew what I was doin'

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