what's the difference between a 10bolt & 12 bolt...?
A stock ls1 is a 10bolt right??

 

Yeah, the stock diff is a 7-5/8", 10-bolt. "10-bolt" refers to 10 bolts that hold the ring gear onto the carrier, and the same applies for the 12-bolt. I can't remember the exact size, but I think the ring gear for a 12-bolt has an I.D. (inside diameter) of 8-3/4". Regardless, it's bigger, and more robust than the smaller 10-bolt setup. Also, I'm sure that the pinion and axle shafts & splines are probably thicker, and stronger as well.

 

So would i be able to install 3.73's, 3200 stall and a shift kit on my stock ss?

 

2 bolts?

Seriously, it is just a shorthand way to identify the various diffs. I think most people refer to the number of cover bolts when describing a diff as a "xx-bolt". On many of the GM diffs, the number of ring gear bolts and cover bolts is the same, but not all. And there is a large number of "10-bolt" diffs with completely different ring gears and ring and pinions. Look at http://www.ring-pinion.com/docs/randpcat.pdf for some examples. You will see 10-bolts with ring gear diameters of 7.5", 7.75", 8.0", 8.2", 8.5" and 8.6". Similarly, wrt "12-bolts" there are diffs with 8.875", 9.25" and 9.5" ring gears.

The 10-bolt in a 4th gen has 10 cover bolts, 10 7/16" ring gear bolts, and a 7.5" ring gear diameter. There are two different carriers, if you buy a set of 3.73's or 4.11's make sure they are for the correct carrier.

Rich