10 bolt / 12 bolt

What advantages does a 12 bolt have over a 10 bolt. What's the big deal?

the 12 bolt has a much larger ring and pinion gear, that is capable of handling much more power, it also has thicker axles with a higher number of splines, which better put down the power. those are the basic differences.

It also requires more power to use.

does a 91 RS have a 10 bolt? stock?

yes

So, depending on how much horsepower you have, a 10 bolt could fail?

My point is this. My 70 "Z28" should have a 12 bolt in it, but it's only a 10 bolt. Should I be looking at putting a 12 bolt back in there once this thing is running right, or is that just an ego thing? I have no idea what HP it's producing, plan on having it dyno'd just to see.

Im not sure if all Z28s got 12 bolts back then or only ones with certain options. The older 10 bolts were stronger than the ones they used in the later years because I think they have a larger ring gear.

You COULD go back to a 12 bolt or you could look into other aftermarket rearends.

well, 10bolts can handle a good 400hp stock, and your 1970 Z28 should be running a gross 360hp, which is probly closer to around 300-320 net hp. so you should be fine with the ten bolt.

I think the big blocks got the 12 bolt and the small blocks got the 10.

If you have good traction and launch hard though your 10 bolt may not get you very far.