Looking for rear diff info - The 1947 - Present Chevrolet & GMC Truck Message Board Network

evan · 12-01-2010, 07:08 PM

Is there a thread somewhere that has info on what different rear ends were offered on these trucks? Also, how much power they can handle stock and recommendations on how to beef them up?

babyJay · 12-01-2010, 10:17 PM

This may help a little.

THE "10" SILVERADO · 12-01-2010, 10:35 PM

hmm so I either have 2.76, 3.07 or 3.73.....

rblcori7 · 12-01-2010, 11:24 PM

yeppers ive got 3.73's and a 10 bolt

datguysaL · 12-02-2010, 12:01 AM

my 85 c10 swb silverado shows 2.42's for rear end gears according to the glove box label. its a 10 bolt.

evan · 12-02-2010, 05:25 PM

I'm going to be building one truck out of two. One of them has a 10 bolt and the other has a 12 bolt. Is one stronger or more desirable than the other?

thesickc10 · 12-02-2010, 06:11 PM

Quote:

Originally Posted by evan

I'm going to be building one truck out of two. One of them has a 10 bolt and the other has a 12 bolt. Is one stronger or more desirable than the other?

go with the 12 bolt

68 TT · 12-02-2010, 06:35 PM

Use the 10-bolt.

The truck 12-bolt has a smaller diameter pinion bearing and is weaker than the 8-1/2" 10-bolt. The 10-bolt uses the same pinion diameter as the car 12-bolt.

The new body style trucks & SUV's use a larger 30-spline axle in their 8-1/2" 10-bolts so you can easily find 30-spline carriers that will fit into the older 10-bolts as an upgrade to make them nearly as strong as the car 12-bolt.

You will need to buy new axles to put the 30-spline carrier into your older axle housing but for less money you can pick up the whole rear end out of the new body style truck instead.

It is a little wider than the square body part but that is good as it puts the rear wheels closer to being aligned with the front wheel position. All you have to do is remove the perches and relocate them to the right spot for the square body.

520CheyenneK10 · 11-09-2013, 07:46 PM

Quote:

Originally Posted by babyJay

This may help a little.

Now my 73' has the dana 44 front but my 12 bolt rear has 3.07 gearing as does the dana front. according to the chart my rear diff should have something else but I removed the cover and counted and it is stamped with the gear numbers. 14 and 43 which is 3.07

Keith Seymore · 11-10-2013, 01:33 PM

Quote:

Originally Posted by THE "10" SILVERADO

hmm so I either have 2.76, 3.07 or 3.73.....

Base axle will typically not be shown on the SPID (or it will show "GQ1" base axle with no ratio specified).

Optional ratios will show on the SPID, both the RPO code and the noun name (GT4 = 3.73 axle ratio).

K

12-01-2010, 07:08 PM	#1
evan Registered User Join Date: Jul 2005 Location: SK, Canada Posts: 488	Looking for rear diff info Is there a thread somewhere that has info on what different rear ends were offered on these trucks? Also, how much power they can handle stock and recommendations on how to beef them up? __________________ Evan B.

12-01-2010, 10:17 PM	#2
babyJay Arrived on a Pale Horse Join Date: Mar 2007 Location: SnagTown Indiana Posts: 2,524	Re: Looking for rear diff info This may help a little. __________________ Jason 87 V30 350TBI/400 White w/Boss V-plow 89 R3500 CC SRW

12-01-2010, 10:35 PM	#3
THE "10" SILVERADO Registered User Join Date: Sep 2010 Location: Marble Falls, TX Posts: 1,575	Re: Looking for rear diff info hmm so I either have 2.76, 3.07 or 3.73..... __________________ Michael Re-starting the neglected '77...http://67-72chevytrucks.com/vboard/s...=425464&page=9

12-01-2010, 11:24 PM	#4
rblcori7 Registered User Join Date: Jun 2010 Location: Tyndall AFB FL Posts: 214	Re: Looking for rear diff info yeppers ive got 3.73's and a 10 bolt __________________ 84 Short bed 350: Hooker headers, flow master 40 series, edelbrock Intake manifold, Holly street avenger carb, 4 inch skyjacker suspension lift, 33x12.5 Toyo Open Country Mud Terrains, 3.73 gears 2011 Silverado LTZ

12-02-2010, 12:01 AM	#5
datguysaL Registered User Join Date: May 2009 Location: Houston, TX Posts: 155	Re: Looking for rear diff info my 85 c10 swb silverado shows 2.42's for rear end gears according to the glove box label. its a 10 bolt. Last edited by datguysaL; 12-02-2010 at 12:01 AM.

12-02-2010, 05:25 PM	#6
evan Registered User Join Date: Jul 2005 Location: SK, Canada Posts: 488	Re: Looking for rear diff info I'm going to be building one truck out of two. One of them has a 10 bolt and the other has a 12 bolt. Is one stronger or more desirable than the other? __________________ Evan B.

12-02-2010, 06:35 PM	#8
68 TT Still plays with trucks Join Date: Jul 2009 Location: Spokane, WA Posts: 3,556	Re: Looking for rear diff info Use the 10-bolt. The truck 12-bolt has a smaller diameter pinion bearing and is weaker than the 8-1/2" 10-bolt. The 10-bolt uses the same pinion diameter as the car 12-bolt. The new body style trucks & SUV's use a larger 30-spline axle in their 8-1/2" 10-bolts so you can easily find 30-spline carriers that will fit into the older 10-bolts as an upgrade to make them nearly as strong as the car 12-bolt. You will need to buy new axles to put the 30-spline carrier into your older axle housing but for less money you can pick up the whole rear end out of the new body style truck instead. It is a little wider than the square body part but that is good as it puts the rear wheels closer to being aligned with the front wheel position. All you have to do is remove the perches and relocate them to the right spot for the square body. __________________ miSSed opportunity - ground up creation of an AWD 1994 454 SS that never was http://67-72chevytrucks.com/vboard/s...d.php?t=795577 69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been 69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc 68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E 79 Malibu TPI 350 4L60 w/ Z28 steering & sway bars

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