I'm curious about this. My uncle has a buick skylark that has a big block and turbo 400 trans. He runs 10 sec 1/4 mile times with it easy, on slicks, with a trans brake. But his rear end is a 10 bolt, with stronger axles and such. What exactly breaks on the 10 bolt? He said anyone that breaks one doesn't know how to drive

I'm curious due to my dreams of 300 horses (yes, I'll be breaking the tranny first [&:])

 

the old 10bolt was an 8.5" i believe. Our 4th gens got a smaller 7.5" 10 bolt which is much much weaker than the oldies. Your uncle is also running an automatic which is nicer to the rear than a manual (although the transbrake may negate that.....).
the 10bolt housing will actually flex under torque, which brings the gears out of alignment and they shread eachother. It doesnt take much to do this either.

 

His skylark probably has the 8.5" 10 bolt, whereas your 4th gen and my 3rd gen have the 7.5" 10 bolt, the 8.5 is a much stronger axle, however a good 7.5" 10 bolt isn't considered weak until you start getting up around 400 horse.

 

Hmm, so I might be able to get away with stronger axles and a c-clip delete kit?

 

I know the 9 bolt borg warner from the 3rd gens is a much stronger unit, and I know you can put a 4th gen axle in a 3rd gen, but I dont know about vise versa. I think the overall length of the 3rd gen rears are about 2" shorter over all, so you may be able to fix it with the backspacing...

 

The BW 9 bolt is beefier with a 7.75 ring gear and bearing retainers instead of c clips but I think overal lenght is 4 inches shorter so that would be a big spacer on each side to get the wheels out far enough.

And it was most likely brought up before but I must have missed it but, Musicman, Do you drive around with your car smiling at people or is that photoshoped?

 

It's photoshop It would be awesome if the smile was real

Alright, y'all answered my question, thanks. There's different kinds of 10 bolt rear ends, older=stronger.