7.5 or 7 5/8

[mtincher]

How can i tell if my rearend is a 7.5 or 7 5/8 rearend? The truck is a 86 s-10.

[mzoomora]

86 S10 should be 7.5\". The main difference is the axle spline, the 7.5 is 26 spline, and the 7.625 is 28 spline. The case that the ring bolts to is slightly larger on the inside, but the ring gears themselves are the same diameter. All the bearings etc. are also the same. Checking the axle spline is the only way to be sure, because all the ring gears being sold now are the same, so you could have a ring stamped 7.625 in a 7.5 housing.

[mtincher]

Thanks. Do you think that 7.5 or 7 5/8 is strong enough to handle a 355 if we put a posi unit in it?

[mzoomora]

I think a 7.5 is capable of consistant 12\'s depending on how hard it is launched (trans brake, slicks, etc), hard launches will destroy most stock rears. I see plenty of Camaro\'s running 12\'s and even 11\'s with 7.5\'s, and the light weight of the truck helps.