72 3/4 ton rear axle...? - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Rod · 10-08-2005, 11:36 PM

Well

The corporate 3/4 ton and 1 ton diffs had 17 spline.
the heavy duty 11000 lbs special order 1 ton diff had 27 spline.
The dana 60 in these trucks had 30 spline.

BB 3/4 tons had standard equipment 3.54 ratio dana 60's. Optional diffs and ratios could be ordered. In some cases a posi /locker was not an available option if you had a BB. My BB 72 1 ton duallie has a eaton diff 4.10 and detroit locker factory optioned that way...on the glove box.

You could get either dana or corporate under a 3/4 4x4 or a 3/4 ton 2 wd. Leafs were available under both also..but no coils under a 4x4 or a longhorn chassied unit.

4x4Poet · 10-09-2005, 01:39 AM

I'd guess that GM used two different axles in 3/4 ton 2wds because they could order the coil Eaton 2wd axles with just coil spring trailing arm perches and then order D60s with just leaf spring perches. Might have saved money going all one way with each axle. Also, the Eaton's all welded plate axle housing accomdates welded on brackets better, such as for locating arms.

4x4Poet · 10-09-2005, 01:45 AM

BTW, due in most part to some wordy instigator

, we discussed Eaton axles fairly extensively on the 4x4 forum:

http://67-72chevytrucks.com/vboard/s....php3?t=172827

cdyblu · 10-09-2005, 01:53 AM

My 71 had a dana 60 in it (my daughter blew it up doing burnouts) I replaced it with a GM14 bolt, had to move the spring mounts and fab shock mounts.

**RPOZ11** · 10-09-2005, 02:14 AM

4X4 Poet:
You've done some time investigating and investing in all of this info!

I guess I will crawl under the LongHorn and take a few images in the morning of what I have. I do know that that side bolt is there on the drivers side of the pinion/center-section.

The brakes I know are HUGE on this thing; rather surprised me the first time I crawled under her when I was buying it!
With it being ordered as a 1-ton C/30, even the shocks have overload coil springs on them!

I peered at a center-section HO set-up a few weeks ago, passed on it because I really didnt know what I was looking at! I do suppose that the 3:90.1 gear sets from Randy will do me well, as I plan on a Gear Vendors behind the T-400!

Having 2 trucks complicates things, and now I see why the original rear unit was replaced with the 14-bolt unit; cost, availability, and: COST!
That 14-bolt suits me fine, but those welds on the shock mounts still bugg me! Rear Disc set-ups seems to be a familiar changeover for these, even with the rather LARGE rear drums existing on it!

Guess my time now is better suited to dictate what I really have, make choices based upon availability of what I have and then proceed forward.
Looking at restoring my Longhorn has complicated my approach to doing so, and this rear axle situation is becoming problematic, at best for the current moment..........

Decisions, Decisions..........

Rod · 10-09-2005, 10:00 AM

For what you'll pay for a set of 3.90 gears,..I could ship you a 4.10 third member with a detroit locker in it...probably 2 at the cost of those new gears.
I want $300 plus shipping for 4.10 with detroit locker if interested PM me.

**special-K** · 10-09-2005, 10:39 AM

I might have missed this but,make sure the axle this guy has is from 2wd or 4wd.The difference is in the spring perches.Reworking them/reworking the shock mounts,six of one/1/2 dozen of the other.

1969 GMC · 10-09-2005, 01:00 PM

Quote:

Originally Posted by 4x4Poet

I'd guess that GM used two different axles in 3/4 ton 2wds because they could order the coil Eaton 2wd axles with just coil spring trailing arm perches and then order D60s with just leaf spring perches. Might have saved money going all one way with each axle. Also, the Eaton's all welded plate axle housing accomdates welded on brackets better, such as for locating arms.

Actually, I think its because you could order higher gears in the D60. Which you couldn't do in the Eaton.
Someone on here once reasoned that the D60 was stronger than the Eaton because it was under 2wds with the BB. I disagree...its just because of the 3.54 gears. The Eaton was used under all the 1 tons, and just by examining the 2 you can see which is stronger (Eaton). Just the gear problem.

**RPOZ11** · 10-09-2005, 01:54 PM

here is what is under my C/30:

**RPOZ11** · 10-09-2005, 01:54 PM

So I assume that the HO is all a 10-bolt securing pattern....?????

4x4Poet · 10-09-2005, 10:59 PM

Quote:

Originally Posted by 1969 GMC

Actually, I think its because you could order higher gears in the D60. Which you couldn't do in the Eaton.
Someone on here once reasoned that the D60 was stronger than the Eaton because it was under 2wds with the BB. I disagree...its just because of the 3.54 gears. The Eaton was used under all the 1 tons, and just by examining the 2 you can see which is stronger (Eaton). Just the gear problem.

I like your *guess* better...

masterbeavis · 10-10-2005, 09:13 PM

My 52 came from a 71 camper special. It was leaf sprung. 4.57 gears, factory detroit. Sold my open 14B with 4.56 gears, minus shock mounts, and brake lines, for $200. Bought my 52 for $200 the same day.

Both 52 and 72 I own have the ring gear pre load bolt on the side.

86SILVERADO · 10-10-2005, 09:36 PM

Just an FYI last I knew Randys Ring and Pinion no longer makes any new gear sets for the HO72. When I called the best they could do for me was a used 4.10 set and they weren't even sure it was out in the shop. Call around and you may end up having your decision made for you. I ended up pulling a center chunk from a local yard for $100. I got 4.10's and will be putting a 5.14 axle that I have in a parts truck under it soon because the 4.10's just don't cut it for me. I found out I had 5.14's in it originally after I had installed the 4.10's and it makes a huge difference. I am now having to downshift to second on some hills around here with a load where as before I could keep it in third. In second now the thing is screaming and I am climbing at 20 mph and the folks stuck behind me are not happy.

masterbeavis · 10-10-2005, 10:29 PM

Quote:

Originally Posted by Rod

Well

The corporate 3/4 ton and 1 ton diffs had 17 spline.
the heavy duty 11000 lbs special order 1 ton diff had 27 spline.
The dana 60 in these trucks had 30 spline.
.

I thought 60's didnt go 30 spline till after '75? They were 16 spline prior to that, or at least thats how my pre '75 furds all were, Same with the dana 70's, 23 spline prior to 75, 35 spline till?? Is it the same with chebbies?

al's71gmc · 10-10-2005, 11:05 PM

Quote:

Originally Posted by roger0080

From what I recall for 71/72 3/4 Tons is this:

Coil sprung rears got the Eaton HO52
Leaf sprung rears got the Dana 60
The 4x4's have the Eaton HO52 except for 1972 which is Dana 60 (from all the parts books that I can see)

Don't know why 2 rears for the same truck, basically.

My 71 3/4 4x4 gmc has the dana 60....just thought i'd add to the confusion

Fred T · 10-10-2005, 11:32 PM

On the 3.90 gears, Randy had quit making them several years ago, since Art Houser was making them. Art died in Feb., his widow closed the business. I thought that since Randy has added the gears to his website, that he was making them. He had them priced over $500 before, iirc.

On the HO52/72, the main difference is the brakes and drums. The carrier and gears(pumpkin) interchange. AFIK the 10 bolt was dropped with the 73 model.

The shock mount brackets are easy to replace. Find a pair that suits you, then get out the angle grinder and cut the welds on the existing ones. Find someone with a stick welder, drain the lube and put on the new ones.

**RPOZ11** · 10-11-2005, 12:28 AM

Im pretty good on GM stuff, but this is getting sort of confusing to me what was standard issue on these trucks!

4x4Poet · 10-11-2005, 02:01 AM

Quote:

Originally Posted by al's71gmc

My 71 3/4 4x4 gmc has the dana 60....just thought i'd add to the confusion

Sounds right. I distinctly remember several other board members posting on other threads that GMC 4x4 pickups (not burbs) ALL got D60s.

I don't know this for sure myself, though. We need the search function back...

Rod · 10-11-2005, 09:15 AM

I said it earlier in this thread, I'll say it again..you could get either rear diff in a 3/4 4x4 dana or eaton.

1969 GMC · 10-11-2005, 11:53 AM

Quote:

Originally Posted by masterbeavis

I thought 60's didnt go 30 spline till after '75? They were 16 spline prior to that, or at least thats how my pre '75 furds all were, Same with the dana 70's, 23 spline prior to 75, 35 spline till?? Is it the same with chebbies?

Nope, I pulled a shaft on my '69 GMC 3/4 ton 4x4 with the D60 rear, and it has 30 splines. Original axle.

10-08-2005, 11:36 PM	#26
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	Well The corporate 3/4 ton and 1 ton diffs had 17 spline. the heavy duty 11000 lbs special order 1 ton diff had 27 spline. The dana 60 in these trucks had 30 spline. BB 3/4 tons had standard equipment 3.54 ratio dana 60's. Optional diffs and ratios could be ordered. In some cases a posi /locker was not an available option if you had a BB. My BB 72 1 ton duallie has a eaton diff 4.10 and detroit locker factory optioned that way...on the glove box. You could get either dana or corporate under a 3/4 4x4 or a 3/4 ton 2 wd. Leafs were available under both also..but no coils under a 4x4 or a longhorn chassied unit. Last edited by Rod; 10-09-2005 at 12:05 AM.

10-09-2005, 01:39 AM	#27
4x4Poet Registered User Join Date: Nov 2004 Location: "Under Montana skies." Posts: 1,836	I'd guess that GM used two different axles in 3/4 ton 2wds because they could order the coil Eaton 2wd axles with just coil spring trailing arm perches and then order D60s with just leaf spring perches. Might have saved money going all one way with each axle. Also, the Eaton's all welded plate axle housing accomdates welded on brackets better, such as for locating arms. __________________ '71 GMC K20 Suburban, '71 GMC K10 Suburban, '72 Chevy C10 CST Suburban, '72 Chevy K20 clunker pickup.

10-09-2005, 01:45 AM	#28
4x4Poet Registered User Join Date: Nov 2004 Location: "Under Montana skies." Posts: 1,836	BTW, due in most part to some wordy instigator, we discussed Eaton axles fairly extensively on the 4x4 forum: http://67-72chevytrucks.com/vboard/s....php3?t=172827 __________________ '71 GMC K20 Suburban, '71 GMC K10 Suburban, '72 Chevy C10 CST Suburban, '72 Chevy K20 clunker pickup.

10-09-2005, 02:14 AM	#30
RPOZ11 72 BB C30 Super LongHorn Join Date: Nov 2002 Location: Chavez Ravine Posts: 1,606	4X4 Poet: You've done some time investigating and investing in all of this info! I guess I will crawl under the LongHorn and take a few images in the morning of what I have. I do know that that side bolt is there on the drivers side of the pinion/center-section. The brakes I know are HUGE on this thing; rather surprised me the first time I crawled under her when I was buying it! With it being ordered as a 1-ton C/30, even the shocks have overload coil springs on them! I peered at a center-section HO set-up a few weeks ago, passed on it because I really didnt know what I was looking at! I do suppose that the 3:90.1 gear sets from Randy will do me well, as I plan on a Gear Vendors behind the T-400! Having 2 trucks complicates things, and now I see why the original rear unit was replaced with the 14-bolt unit; cost, availability, and: COST! That 14-bolt suits me fine, but those welds on the shock mounts still bugg me! Rear Disc set-ups seems to be a familiar changeover for these, even with the rather LARGE rear drums existing on it! Guess my time now is better suited to dictate what I really have, make choices based upon availability of what I have and then proceed forward. Looking at restoring my Longhorn has complicated my approach to doing so, and this rear axle situation is becoming problematic, at best for the current moment.......... Decisions, Decisions.......... __________________ 72 BB C/30 Longhorn Super HO72 No-Spin, #'s matching, Tilt, Tach, AC, AM/FM HO72 build : http://67-72chevytrucks.com/vboard/s...d.php?t=714492 2017 SS

10-09-2005, 10:39 AM	#32
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,863	I might have missed this but,make sure the axle this guy has is from 2wd or 4wd.The difference is in the spring perches.Reworking them/reworking the shock mounts,six of one/1/2 dozen of the other. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

10-09-2005, 01:53 AM	#29
cdyblu Registered User Join Date: Dec 2004 Location: Green Bay, WI Posts: 44	My 71 had a dana 60 in it (my daughter blew it up doing burnouts) I replaced it with a GM14 bolt, had to move the spring mounts and fab shock mounts.

10-09-2005, 10:00 AM	#31
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	For what you'll pay for a set of 3.90 gears,..I could ship you a 4.10 third member with a detroit locker in it...probably 2 at the cost of those new gears. I want $300 plus shipping for 4.10 with detroit locker if interested PM me.

10-09-2005, 01:54 PM	#34
RPOZ11 72 BB C30 Super LongHorn Join Date: Nov 2002 Location: Chavez Ravine Posts: 1,606	here is what is under my C/30: Attached Images __________________ 72 BB C/30 Longhorn Super HO72 No-Spin, #'s matching, Tilt, Tach, AC, AM/FM HO72 build : http://67-72chevytrucks.com/vboard/s...d.php?t=714492 2017 SS

10-10-2005, 09:13 PM	#37
masterbeavis Having issues Join Date: Jul 2005 Location: Eldorado Ca, an hour east of sacramento Posts: 696	My 52 came from a 71 camper special. It was leaf sprung. 4.57 gears, factory detroit. Sold my open 14B with 4.56 gears, minus shock mounts, and brake lines, for $200. Bought my 52 for $200 the same day. Both 52 and 72 I own have the ring gear pre load bolt on the side. __________________ Quando Omni Flunkus Moritati. The Man's Prayer: "I'm a man, but I can change, if I have to, I guess."

10-10-2005, 09:36 PM	#38
86SILVERADO Registered User Join Date: Dec 2002 Location: Hills of Western Mass Posts: 626	Just an FYI last I knew Randys Ring and Pinion no longer makes any new gear sets for the HO72. When I called the best they could do for me was a used 4.10 set and they weren't even sure it was out in the shop. Call around and you may end up having your decision made for you. I ended up pulling a center chunk from a local yard for $100. I got 4.10's and will be putting a 5.14 axle that I have in a parts truck under it soon because the 4.10's just don't cut it for me. I found out I had 5.14's in it originally after I had installed the 4.10's and it makes a huge difference. I am now having to downshift to second on some hills around here with a load where as before I could keep it in third. In second now the thing is screaming and I am climbing at 20 mph and the folks stuck behind me are not happy. __________________ 86 Silverado C10 back to 305 power! 67 C30 Dually Dump, with 350 transplant, Rockhauler 05 Duramax 3500 "If at first you don't succeed, try a bigger hammer" Member of the 1-Ton club!

10-10-2005, 11:32 PM	#41
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	On the 3.90 gears, Randy had quit making them several years ago, since Art Houser was making them. Art died in Feb., his widow closed the business. I thought that since Randy has added the gears to his website, that he was making them. He had them priced over $500 before, iirc. On the HO52/72, the main difference is the brakes and drums. The carrier and gears(pumpkin) interchange. AFIK the 10 bolt was dropped with the 73 model. The shock mount brackets are easy to replace. Find a pair that suits you, then get out the angle grinder and cut the welds on the existing ones. Find someone with a stick welder, drain the lube and put on the new ones. __________________ Fred There is no such thing as too much cam...just not enough engine.

10-11-2005, 12:28 AM	#42
RPOZ11 72 BB C30 Super LongHorn Join Date: Nov 2002 Location: Chavez Ravine Posts: 1,606	Im pretty good on GM stuff, but this is getting sort of confusing to me what was standard issue on these trucks! __________________ 72 BB C/30 Longhorn Super HO72 No-Spin, #'s matching, Tilt, Tach, AC, AM/FM HO72 build : http://67-72chevytrucks.com/vboard/s...d.php?t=714492 2017 SS

10-11-2005, 09:15 AM	#44
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	I said it earlier in this thread, I'll say it again..you could get either rear diff in a 3/4 4x4 dana or eaton.



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