8 3/4" How Strong?

Murray said
My first time with big power. '68 Dart, 606hp sbm, Tremec, Gerst suspension. Want to run autocross, but streetable. Do you think an 8 3/4" is a good choice? Will it handle 600+ hp? Maybe a "built" 8 3/4"? What do you think? Thanks.

It’s more of the amount of torque vs weight and the “Hook” of the vehicle and of course, the amount of abuse. This is a very blurry line to have anyone make a call on. It seems that around the 600+ ft. Lbs. of torque and a 3600 lbs car, the ghost is given up after a short time. Sometimes more, sometimes less. Dropping the car weight would help a lot in longevity as well as beefing up the rear.

I would not bother beefing up the rear beyond high strength axles and braces across the back side and the spring perches. These are cheap and easy DIY jobs with a welder. Of course the 3rd member is upgraded with a new carrier and gears to suite the task at hand, but that’s the case with me on any gear change I do with this rear. I don’t consider this part of the price upgrade tag but just par for the course since the OE stuff, I tend to break.

Go to doctor Diff and have a poke around.