How much WHP/WTQ will a STOCK one of these take before I blow it apart.
I plan on doing a LS swap for my project Firebird

 

.5 hp

 

Considering that a 250hp Gen-1 350 can break it, it definitely won't take the power of a LS...

 

You can destroy one of these rears with a 6-cylinder if you get traction and have a sticky clutch. It can last forever with a big block if you drive it like there's an egg between your foot and the skinny pedal.

Open and all the rest of that, doesn't make much difference. 26 vs 28 spline axles (88-back vs 90-up) makes a minor difference. Although, if you had a Gov-Bomb, it would be REALLY fragile. You could probably tear one of THOSE up with your lawn mower if you really put your mind to it.

But it's not like anybody can tell you, at 274.38 wheel horsepucker and 271.76 torques, it'll last forever; but if you exceed 279.21 horsepucker and/or 286.55 torques, the matter will meet the anti-matter and begin the irreversible Republican/Democratic annihilation and the entire known universe will disappear into a black hole centered on your driveway. It just doesn't work that way.

 

With an open diff and stock width tires, you aren't likely to find enough traction to end it's life on the test drive..... But you might if you try hard enough.

It's not that strong of a diff. That's why even the mildly powerful cars with a "hot' 200 hp 305 TPI got the 9 bolt, or later the beefed up 28 spline 10 bolt.

With some upgrades it might live. 28 spline axles, a Torsen carrier, good quality gears, proper setup and a girdle cover. My 9 bolt is original to my 86 Trans Am and is upgraded in these places. I have about 325 HP at the rear wheels and I drive like a total *** at all times. I'm about to strap on a Procharger, probably some 305-315's to get some reasonable traction.... I guess we shall see how strong it is. LoL. If I shred it then I'll go to a Strange Dana 60.

GD

 

Traction and wheel hop is what breaks a 10 bolt. There are tens of thousands, if not hundreds of thousands of ls1 4th gens and swapped 3rd gens out there with a 10 bolt and doing just fine.

 

I don’t know if welding the axle tubes to the housing carrier actually does any good but I did that to my 9 bolt I’m going to be using for my 383.