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10 bolt to 12 bolt swap
I have an 87 R10 with a 10 bolt rear, I want to swap it out for a 12 bolt. Will any rear end from 73 to 87 interchange? If I find a 12 bolt from an earlier truck, will it be a direct bolt-in for my 87? Thanks.
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Re: 10 bolt to 12 bolt swap
Yes its a bolt in swap, but you will need a conversion u-joint.
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Re: 10 bolt to 12 bolt swap
You have to worry bout how wide the rear end is from diff models just cant bolt it in an go
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Re: 10 bolt to 12 bolt swap
Thank you sir. I thought that was the case, just needed confirmation from somebody that knows these trucks better than me. Thanks again.
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Re: 10 bolt to 12 bolt swap
Are they generally wider than the 10 bolts?
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Re: 10 bolt to 12 bolt swap
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Re: 10 bolt to 12 bolt swap
I've wondered about this swap as well (but in the opposite direction). Would anyone know if the driveshaft length is the same between the two?
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Re: 10 bolt to 12 bolt swap
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I just grabed one. Mine hasn't seen the road yeat but it is bagged and i haven't had any problems
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Re: 10 bolt to 12 bolt swap
I was under the impression that they were the same widths as well.
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Re: 10 bolt to 12 bolt swap
autozone part# 3-3130 might be the combo ujoint you need. i ended up putting a 77 drivetrain into a 84 k5 blazer, used everything but the 12 bolt rear end so it might work backwards?
it gets kind difficult telling parts store guys that you need a universal universal joint so you can try that number and see if its the one you need |
Re: 10 bolt to 12 bolt swap
2wd vs 4wd might be different width, I know it is for 88-98's. That and the u joint, otherwise they bolt right in. Not really much stronger then the oem 10bolt though so I'm not sure the point besides bragging rights?
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Re: 10 bolt to 12 bolt swap
Tom nailed it on the head. The truck 12 bolt has a pinion shaft diameter of 1.438 and the 8.5 10 bolt has a pinion shaft diameter of 1.625 leading many to argue that the 8.5 10 bolt is actually stronger. I've had a 8.5 10 bolt that lived (a long life) in a low 10 second full steel body malibu that made over 700 from a stroked big block that also made crazy torque. I don't believe that going from a 8.5 10 bolt to a 12 bolt truck rear end is an upgrade. There is a reason that GM is still running basically the same rear in ever 1/2 ton vehicle they build.
Mike |
Re: 10 bolt to 12 bolt swap
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Re: 10 bolt to 12 bolt swap
At this point I am just planning ahead, I want to change my gears and install a posi. The reason I am considering a 12 bolt is because a friend has a posi for one. I think I will be better off keeping my 10 bolt.
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Re: 10 bolt to 12 bolt swap
Currently doing this swap, 10 to 12 bolt in my wife's 86. Had a good 12 bolt with a 3.08 posi (good eaton not a gov loc). Decided it was cheaper to put 3.73s in the 12 bolt than to buy a posi and gears to replace the 2.73s in the open 10 bolt.
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Re: 10 bolt to 12 bolt swap
The 12 bolt has a carrier break between 3.42:1 and 3.73:1, so you won't be able to use the eaton posi with 3.73 gears. That's another area where the 10 bolt is better. There is no carrier break for the 8.5.
Mike |
Re: 10 bolt to 12 bolt swap
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Re: 10 bolt to 12 bolt swap
I swapped the 10 bolt in my '83 for a 12 bolt from a '79 and only needed to change the U-joint. The U joint on the 10 bolt was actually larger than the one on the 12 bolt. In hindsight, I wish I would have kept the 10 bolt or swapped in a 10 bolt from a '91 'Burb with the larger axles.
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Re: 10 bolt to 12 bolt swap
If I remember right 82 up only have the 10 bolt.
73-81 you could get the 12 bolt |
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