10 bolt vs 12bolt GM rear - The 1947 - Present Chevrolet & GMC Truck Message Board Network

remist17 · 05-09-2011, 02:32 PM

Need some help. I have a 10 bolt in my 87 short bed step pickup with 3.08 gears. I also have a 12 bolt out of a 1976 1/2 ton long bed with 3.73 with a locker.

Will the 12 bolt bolt in the 87? Are the spring perches the same?

Also I am looking for rims for the truck. I dont know if the 12 bolt has the same back spacing and bolt pattern as the 10 bolt. The 10 bolt is a 5 bolt 3 3/4" backspace.

Any help on this?

Jonboy · 05-09-2011, 03:23 PM

It is a direct bolt in. The only problem you might face is the rear u-joint. Seems that the yoke on a 12 bolt uses a larger u-joint than a 10 bolt. You can get a conversion u-joint from NAPA to correct this.

gchemist · 05-09-2011, 09:28 PM

I swapped in a 77 12 bolt into my 83. It's a directy swap. You do need a conversion ujoint. The 10 caps are larger than the 12 bolt caps. If the locker a GM gov-loc? Gov-locs don't last very long. They blow up all the time.

rare86 · 05-09-2011, 09:44 PM

also, If the 76 axle has the 2 inch drums, you can swap out the back plates, drums, and hardware from the 87 axle and keep the larger brakes that the 87 should have. I did and it was as easy as pulling the axles out and swapping the back plates over. The larger drums and shoes are easier to find than the 2 inch.. At least in my area they are.

Altec · 05-09-2011, 10:03 PM

Quote:

Originally Posted by Jonboy

It is a direct bolt in. The only problem you might face is the rear u-joint. Seems that the yoke on a 12 bolt uses a larger u-joint than a 10 bolt. You can get a conversion u-joint from NAPA to correct this.

Smaller, if you can believe that...

There is a thread in the 4x4 section on the first page where I posted the part number. I just did this very swap.

remist17 · 05-10-2011, 12:12 PM

the locker is a lockrite by richmond. Aftermarket.

So the offset for the rims are the same from 10 bolt to 12 bolt?

silvereagle07 · 05-10-2011, 12:23 PM

yeah they are the same. Ive swapped them in my 84.

remist17 · 05-11-2011, 10:06 AM

good to know. Thanks all

05-09-2011, 02:32 PM	#1
remist17 Registered User Join Date: Jul 2009 Location: PA Posts: 406	10 bolt vs 12bolt GM rear Need some help. I have a 10 bolt in my 87 short bed step pickup with 3.08 gears. I also have a 12 bolt out of a 1976 1/2 ton long bed with 3.73 with a locker. Will the 12 bolt bolt in the 87? Are the spring perches the same? Also I am looking for rims for the truck. I dont know if the 12 bolt has the same back spacing and bolt pattern as the 10 bolt. The 10 bolt is a 5 bolt 3 3/4" backspace. Any help on this? __________________ 2013 Chevy Silverado, Z71, 5.3L, 4 door 2005 Chevy Silverado, Z71, 5.3L, 4 door, 3.40 Support the Troops.

05-09-2011, 03:23 PM	#2
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	Re: 10 bolt vs 12bolt GM rear It is a direct bolt in. The only problem you might face is the rear u-joint. Seems that the yoke on a 12 bolt uses a larger u-joint than a 10 bolt. You can get a conversion u-joint from NAPA to correct this. __________________ 1974 Jimmy- 5.3/4L80e/NP241

05-09-2011, 09:28 PM	#3
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	Re: 10 bolt vs 12bolt GM rear I swapped in a 77 12 bolt into my 83. It's a directy swap. You do need a conversion ujoint. The 10 caps are larger than the 12 bolt caps. If the locker a GM gov-loc? Gov-locs don't last very long. They blow up all the time. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

05-09-2011, 09:44 PM	#4
rare86 Extended cab fanatic Join Date: Oct 2009 Location: Gardendale, Tx Posts: 314	Re: 10 bolt vs 12bolt GM rear also, If the 76 axle has the 2 inch drums, you can swap out the back plates, drums, and hardware from the 87 axle and keep the larger brakes that the 87 should have. I did and it was as easy as pulling the axles out and swapping the back plates over. The larger drums and shoes are easier to find than the 2 inch.. At least in my area they are. __________________ If it has a motor, it has my attention.

05-10-2011, 12:12 PM	#6
remist17 Registered User Join Date: Jul 2009 Location: PA Posts: 406	Re: 10 bolt vs 12bolt GM rear the locker is a lockrite by richmond. Aftermarket. So the offset for the rims are the same from 10 bolt to 12 bolt? __________________ 2013 Chevy Silverado, Z71, 5.3L, 4 door 2005 Chevy Silverado, Z71, 5.3L, 4 door, 3.40 Support the Troops. Last edited by remist17; 05-10-2011 at 12:13 PM.

05-10-2011, 12:23 PM	#7
silvereagle07 Registered User Join Date: Sep 2008 Location: Bailey, NC Posts: 2,462	Re: 10 bolt vs 12bolt GM rear yeah they are the same. Ive swapped them in my 84. __________________ Jeramy '84 GMC project truck '85 Chevy 4X4 SOLD '07 Chevy Trailblazer SS 5th Annual SHPHC Car/Truck Show Pics http://67-72chevytrucks.com/vboard/s...d.php?t=543605 UPDATED PICS! CHECK 'EM OUT

05-11-2011, 10:06 AM	#8
remist17 Registered User Join Date: Jul 2009 Location: PA Posts: 406	Re: 10 bolt vs 12bolt GM rear good to know. Thanks all __________________ 2013 Chevy Silverado, Z71, 5.3L, 4 door 2005 Chevy Silverado, Z71, 5.3L, 4 door, 3.40 Support the Troops.

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