Differential question

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Feb 2, 2007 | 09:08 PM

81cali

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Burning Brakes

Joined: Feb 2006

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From: High Desert California

Differential question

Will a differential from a 1986 fit a 1981? My car is auto but will be doing a T10 swap and I don't think those stock gears will move. I have a vortec motor in it with a good size cam, performer RPM intake, 750 carb, headers, and true duals. Maybe upgrade to 3.55 gears, what do you guys think?

Feb 2, 2007 | 09:19 PM

StickShiftCorvette

Drifting

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I'd bet against it.

I think the diff was all new for MY '84.

Feb 2, 2007 | 10:04 PM

wfo76

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From: MS

Don't think it will work either

The ratios for 80-82 are a little different and there is a 3.31 that will work with the T10 and still give you decent highway cruising or you could do the 3.54. Wouldn't go any lower than 3.54 without overdrive. Which T10 you going with, 2.88, 2.64 or 2.43 first gear?

Feb 2, 2007 | 11:44 PM

81cali

Thread Starter

Burning Brakes

Joined: Feb 2006

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From: High Desert California

Guess I can go with a 3.54 or 3.55

Feb 2, 2007 | 11:52 PM

wfo76

Drifting

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From: MS

No 3.55 for 80-82, it's a 3.54

80-82 ratios according to Tom's Differentials

2.72*
2.87*
3.07
3.23*
3.31
3.42*
3.54
3.73
3.92
4.09
4.27
4.55
4.78*
4.89*
5.13
5.38
5.89

*discontinued

Feb 2, 2007 | 11:58 PM

81cali

Thread Starter

Burning Brakes

Joined: Feb 2006

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From: High Desert California

cool, would it be cheaper to get the gears and throw them in or chance my way and wait for someone selling a used one with that gearing ratio?

Feb 3, 2007 | 11:05 AM

GTR1999

Tech Contributor

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From: Connecticut, USA

If you're going to build the power up and push the car you'd be better off swapping for an 71-79 iron unit and building it first. Then you'll have a better unit then any stock one. If you want the stock aluminum one built let Mike Traccdog know, he rebuilds the 80-82's all the time.

Feb 3, 2007 | 01:03 PM

tracdogg2

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From: Garland Texas

The C4 dana is considerably stronger than the 80-82 but it does not use a front mount. Instead it uses a torque arm to the trans. I think the only person who has done this swap is Twin Turbo but his frame is heavily modded. As Gary said swap in the 75-79 cast iron unit with the 3 inch halfshafts. 65-74 uses 2 1/2 inch halfshafts but will also work.
Mike