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#1 |
Registered User
Join Date: Mar 2014
Location: Mt Dora FL
Posts: 68
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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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#2 |
Registered User
Join Date: Jan 2007
Location: Garland,TX
Posts: 431
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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.
__________________
80 C10 SWB Step Side - 350 w/ vortec heads, TH350, 12-bolt 3.73 |
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#3 |
Diggin The SquareLife
Join Date: Dec 2010
Location: garland,tx
Posts: 1,933
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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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#4 |
Watch out for your cornhole !
![]() Join Date: Jun 2003
Location: Azle, Texas
Posts: 14,162
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Re: 10 bolt to 12 bolt swap
Explain please ? It sounds like you're saying that 73-87 there were different widths.
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I'm on the Instagram- @Gearhead_Kevin |
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#5 |
Registered User
Join Date: Feb 2005
Location: Saskatoon, SK
Posts: 97
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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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#6 |
Registered User
Join Date: Jan 2007
Location: Garland,TX
Posts: 431
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Re: 10 bolt to 12 bolt swap
They should be, I used a driveshaft out of a swb with a 10 bolt and used it on my 12 bolt. Donor truck also had a th350.
__________________
80 C10 SWB Step Side - 350 w/ vortec heads, TH350, 12-bolt 3.73 |
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#7 |
Registered User
Join Date: Mar 2014
Location: Mt Dora FL
Posts: 68
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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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#8 |
Registered User
Join Date: Mar 2014
Location: Mt Dora FL
Posts: 68
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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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#9 |
Registered User
Join Date: Mar 2014
Location: Mt Dora FL
Posts: 68
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Re: 10 bolt to 12 bolt swap
Are they generally wider than the 10 bolts?
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#10 |
Registered User
Join Date: Nov 2011
Location: Oklahoma City Oklahoma
Posts: 1,056
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Re: 10 bolt to 12 bolt swap
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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#11 |
Registered User
Join Date: Jul 2016
Location: Brandon,MS
Posts: 489
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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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#12 |
Registered User
Join Date: Jan 2017
Location: wheaton IL
Posts: 659
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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 |
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#13 |
driving is in my blood
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,720
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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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-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
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#14 |
Registered User
Join Date: Jul 2007
Location: Sims, NC
Posts: 531
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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
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All things Chevy truck: 1986 SWB "Jolene" boosted 5.3/4l80e project |
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#15 |
Registered User
Join Date: Mar 2007
Location: Farmington, MN
Posts: 928
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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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I can still count my vehicles on two... wait three hands. |
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#16 |
Registered User
Join Date: Oct 2015
Location: Ottawa, Ontario, Canada
Posts: 752
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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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![]() Was a 77 454 w/308 gear. Taken out 550 lbs. up front with motor clip change. |
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