I have a 1986 IROC I bought It bone stock almost with a 305TPI headers and a 700r4 273 limit slip rear end, it ran a 15.14 @91mph for best time, scince then I have got the trans rebuilt corvette servos transgo shift kit and 2400 stall the 305 was pulled out and I have a 383 Stroker 10.8 to 1 compression forged pistons rods 906 Vortec heads elgin Cam 484/484 lift RPM air gap intake holley 750 DP carb still has the stock rear end.. wondering what you guys think I will run with the stock rear end and afterwards when I put in a locker and 373s

Assuming you have traction and a decent tune, you should be in the mid- to high-12s with the 2.73s. With 3.73s and traction, probably low-12s, maybe high-11s. I'd want more stall, though, to insure running those numbers.

BTW, when you put in the 3.73 gears and locker, get 28 spline axles.

will thouse work with my rear end scince its 26 now?


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You would have to just order a 28 spline locker instead of a 26(if you bought the 28 spline axles). Also, I would think that even with a locker and 3.73 gear my prediction would be around 12.6. I agree with five7kid that with a bigger stall you would be a lot better off.

Yes, like Greggy said. You can "even" go up from 7-1/2" gears to 7-5/8" gears.

I did all this in my '83 rear, originally with open 2.73 gears and 26 spline axles.

You may want to consider a Detroit Truetrac rather than a run-of-the-mill posi like Eaton. I just discovered broken off posi disk tabs in mine. It'll get a Truetrac next week.

I deffinetly wont cheap out on the rear end, no point in spending money on cheap parts


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Unfortunately, expensive parts do not necessarily equate to longevity when you are talking 7.5" GM rear ends. I've seen dozens of ring gear failures and even a few bearing problems (I spun the pinion race once myself) that honestly relegate these rears to the "want a stock rear for originality" category. I've never seen a broken axle in person, although have seen a few c-clips fail. I nuked 2 7.5" rears driving normally with a 300hp 350, yours will be more powerful and have more TQ.

My suggestion is to find a 3.23, 3.42, or 3.73 factory 10 bolt for the 3rd gens and swap it in - no reason to spend $1k to break it the same as a factory stock rear IMO.

car ran a 13.40 @ 105 un tuned and trans shifting to early Im sure to see 12s after the tunning and issues are worked out

13.11 @ 106mph now has Detroit locker 342gears LCA with relocation brackets easy 2.0 lauches other wise it wheel hops