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Old 07-27-2021, 10:58 AM   #1
Rick257
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Rear end swap

Be gentle Im new.... I have a 72 c10 3.07 open rear end.. want to go to 4.11 posi.. I had a shop try to rebuild mine.. no joy.. My question is... what mod year rear ends will fit?

Thanks
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Old 07-27-2021, 11:01 AM   #2
Ziegelsteinfaust
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Re: Rear end swap

Why couldn't a shop rebuild yours?
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Old 07-27-2021, 11:04 AM   #3
Rick257
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Re: Rear end swap

He couldnt get it to run quiet... said no matter what he did it howled...
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Old 07-27-2021, 11:04 AM   #4
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Re: Rear end swap

There are many ways to skin this cat. Tell us some more about your truck, drivetrain setup, and your budget for this so we can guide you in the right direction.
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Old 07-27-2021, 11:07 AM   #5
Rick257
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Re: Rear end swap

truck is a 72... new chevy crate 350 approx 275 hp with phoenix trans 700r4.. This is a toy.. I want to be able to bark tires when shifting to second (I know Ill need a few more horses for that) not to drag race
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Old 07-27-2021, 11:09 AM   #6
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Re: Rear end swap

as to budget... I dont have any idea what is rerasonable
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Old 07-27-2021, 11:16 AM   #7
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Re: Rear end swap

What posi carrier and gears did you already buy ?
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Old 07-27-2021, 11:20 AM   #8
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Re: Rear end swap

Not sure he bought all parts and kept the carrier and gears... pinion threads were ruined ( I didnt pay for any of it)
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Old 07-27-2021, 11:23 AM   #9
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Re: Rear end swap

Find another drive line shop .

https://www.google.com/search?client...fi=hd:;si:;mv:[[43.92911680624769,-115.63658225078125],[43.30175797666833,-117.25706564921875],null,[43.616255535942095,-116.44682395],10]
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Old 07-27-2021, 11:23 AM   #10
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Re: Rear end swap

A knowledgeable mechanic can fix your existing rear end with new parts and get you what you want. It sounds like the previous mechanic doesn't know how to set pinion pre-load or had the wrong parts. If he doesn't know why its howling, then that is a sure sign he is in over his head.

I'd get a new mechanic that specializes in rear ends. I think this could be done with new performance parts for $1,200 with a reputable shop.

You need a good firm tranny shift kit to bark tires with a mild 350.
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Old 07-27-2021, 11:39 AM   #11
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Re: Rear end swap

I have seen brand new Ring and Pinion gear sets howl. Nothing could be done to fix it. Had to just get a new set.
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Old 07-27-2021, 03:33 PM   #12
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Re: Rear end swap

Quote:
Originally Posted by BigBird05 View Post
I have seen brand new Ring and Pinion gear sets howl. Nothing could be done to fix it. Had to just get a new set.
I just went through this whole process - shop owner wanted to blame the transmission for the new whine and howl. New owner taking ownership of the shop was a stand-up guy and fixed it all for me. The Sierra gear set was set up twice with no change - New Yukon gear set with the new Eaton Posi was the solution...
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Old 07-27-2021, 04:11 PM   #13
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Re: Rear end swap

Quote:
Originally Posted by OregonNed View Post
I just went through this whole process - shop owner wanted to blame the transmission for the new whine and howl. New owner taking ownership of the shop was a stand-up guy and fixed it all for me. The Sierra gear set was set up twice with no change - New Yukon gear set with the new Eaton Posi was the solution...
Set up my own with Yukon parts and no howl.
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Old 07-27-2021, 04:59 PM   #14
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Re: Rear end swap

Quote:
Originally Posted by BigBird05 View Post
I have seen brand new Ring and Pinion gear sets howl. Nothing could be done to fix it. Had to just get a new set.
Cheap sets with less fine machining can howl vs expensive sets. Provided they are installed correctly. I called Richmond gear, and Motive to verify.

I use the cheap sets on trucks, and expensive on cars. Due to interior sound levels.
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Old 07-28-2021, 04:42 AM   #15
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Re: Rear end swap

Late 70 through 72 will be a direct swap for the rear end housing. It will be 57" long measured from the inside edge of one rear brake backing plate over to the other side in the same spot. (If you go that route)

Earlier rear end housings will be .75" more narrow on each side so it will impact your wheel backspacing a little. It will work, they're just a bit more narrow than 70-72.

But, personally I'd just have yours built. As others have mentioned I'd find another shop.

With your setup I'd put a shift kit in the trans and 3.73 posi rear. Gas mileage will be brutal with either 3.73 or 4.11 but .. 3.73 might help the wallet a little and still get your truck out of the hole a little quicker.

Do you do any freeway driving at all or ever plan to? Do you do any towing?
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Old 07-28-2021, 07:10 AM   #16
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Re: Rear end swap

I have all the necessary tools to do the job myself...and I have done several for others
Good gears will not "howl" or "whine" even when brand new...
A few thousandths of an inch make a lot of difference on precision made gears.
Swapping in a used axle is like a "pig-in-a-poke" it may not be any good either.
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Old 07-28-2021, 08:13 AM   #17
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Re: Rear end swap

3.73 or 4.10 should be fine on MPG with an OD. Its easier to get rolling and OD cuts the RPM down to reasonable at speed. My personal experience has almost always shown lugging was worse than RPM within reason. Obviously short tires and 5.14 gears with a low RPM motor will be way out of efficiency range on the highway. Low 2000 RPMs seem to work really well for a cruise RPM if the motor is somewhat stock. If you live in a hilly area then a couple of extra RPMs won't hurt.

My old blazer got about the same MPG with 3.07 as it did with 3.73s. A manual trans swap was the biggest help In all the drivetrains it saw. Full time 4x4 to part time. Stock 400sb, built 400sb, stock 350, t350 to sm465. Original was 6 MPG and got a best around 15MPG when built 400sb, 4spd, and part time 4x4. Gear swap was after the stock 350 went in but MPG was constant at approx 12MPG.
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Old 07-28-2021, 01:47 PM   #18
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Re: Rear end swap

If I was to go the cheap SOB route, I would get an explorer 8.8 with rear disc brakes, factree trac lock, and 3.73 gears from a junkyard, then drill the axle flanges for the chevy 5 bolt pattern and move the wheel studs to them. I would then upgrade the factory trac loc limited slip discs to carbon fibre limited slip disc plates to make a fairly stout non slip set-up. If the 8.8 was a little narrower I bet I could find wheels with an offset that would match the outside width of the tires to stock C10. Then I would grind off all the explorer mounts and weld in new spring perches and shock mounts. You might need to modify your rear driveline to accept the Ford U joint or get a conversion U-joint. The ford 8.8 is a fairly common swap into other cars so lots of aftermarket support and conversion parts.

There are tons of explorers at the junkyard around me and most still have the rear axles. There were 3.73 and even some 4:11 in explorers. The early 90s ones have rear drums if you don't want to run rear discs. I think all of them came with the trac-loc limited slip system, which is tough unless you want to only drag race.

There is also the Crown Vic 8.8 which is a little wider and has the tougher 31 spline axles, but most are 3.55 ratio. The 8.8 also came in F-150s and later Broncos. Not sure which one would have the correct width for a C10.
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Old 07-28-2021, 03:52 PM   #19
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Re: Rear end swap

Or , You could buy the carrier and gears and a magnetic dial indicator and do it yourself and save some cash !

https://www.ebay.com/itm/13190008181...RoCfPkQAvD_BwE
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Old 07-28-2021, 07:40 PM   #20
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Re: Rear end swap

Explorer 8.8 have 31 splines but rangers do not. The nice thing about this axle is no need to swap carriers and it can go down into the 6s for gears. The cast iron shims are kind of a pita! The rear discs truthfully suck and are under sized. Nice axle though and have one under a jeep. Way better than a dana 35.
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Old 07-30-2021, 02:47 AM   #21
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Re: Rear end swap

Just did my first gear change ever on my 94 C1500. Used Yukon parts. Few hundred miles and all is good so far. Digital caliper and the dial gauge were not in my tool arsenal. Less than $100 at HF for both. If you shop sure can be had for less as Grumpy OM showed. It was good practice for the AAM 11.5 in my 72 which is next.
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Old 07-30-2021, 08:00 AM   #22
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Re: Rear end swap

Depending on shim location for the pinion a harbor freight gear puller can be nice also. The one with the bearing cups that slide in from the side and then pressure pulls straight up on that. You may have to pull the new bearing back off for a shim adjustment and if you roach the bearing then you need a new bearing. Also if you can get the old bearings off in one piece you can grind the ID to make setup bearings. That makes shim adjustments easy. Once you get it dialed in switch to the new bearings and double check.
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Old 08-01-2021, 09:59 PM   #23
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Re: Rear end swap

I have a 72 with 275hp 350, 700r4 and 4.11 single trac diff. The 4.11 gives it a tendency to pull to the right---at every gas station!
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