Does my 84 Z28 have a 9 bolt or 10 bolt rear?and what ever it is,how much HP can it with stand?

 

It has a 10 bolt. How much power it will survive depends on how it's abused.

 

so a 10 bolt is good?and the bigger the # of rear the better it is like 9,10,12 bolt.hate to sound like a dumb ***,but i'd like to know

 

The number of bolts is just something used to conveniently identify the rear, it doesn't directly indicate the strength. GM has even used a number of different 10 bolt rears over the years, and the one used in the early thirgens is by far the weakest.

Third and fourth generation 10 bolt rears have 7.5" or 7.625" diameter ring gears. To some extent, the size of the ring gear indicates the strength of the transmission. Early thirdgen rears also have smaller 26 spline axles, while later thirdgen and fourthgen rears use stringer 28 spline axles.

The other stock rear used was the 9 bolt, with a 7.75" ring gear. For a lot of other reasons, the 9 bolt is stronger than the 10 bolt, but parts are much harder to find.

GM also offered a Dana 44 rear end that wasn't used in factory cars, but could be bought from the performance parts catalog. It uses an 8.5" ring gear.

 

GM also offered a Dana 44 rear end that wasn't used in factory cars, but could be bought from the performance parts catalog. It uses an 8.5" ring gear.[/QUOTE]

Can we say it's a second gen diff. into a third gen !!!

 

what rear does my august 89 born 90 iroc have? ive been told august and september are the last of the 9 bolt

 

Look at the back cover, if it has a rubber plug in it, then it is a 9-bolt.