I have the 10 bolt rear, 3:42, or some similar aftermarket rear judging by my rpms. I am building a moderate vortec 350 and wanna know what the 10 bolt can handle? I've read on it, and I get mixed results in regards to the durability of this rear end. Any input? And what's the spline count for the ones in the IROC's, as I understand 2 different versions exist. Thanks!

 

The spline counts were not dependent on the engine or trim package(RS/IROC/Z28) of the car. All cars had the 26 spline axles till 88 or 89, I believe it was 89, and cars made after that got the 28 spline axles.

As for power handling, it depends on what you do with it. 350-400HP is usually safe, unless you are running slicks. Abusing the rear end will also break it, as with most things.

 

Some guys have broke them with a stock 305 and others have run over 400 HP and they survived. It's impossible to say what it will handle, but most of the time if you only use hard street tires and don't have any wheel hop they will hold up pretty well.

 

Hmm, interesting, thanks guys!

 

I'd say with an automatic trans and street tires, you will be just fine.