Best bet on rear suspension?

A Dana 60 is about 70 pounds heavier than an 8.75, but since you're going to narrow it, you may lop off enough to get it down close to the stock 8.75 A body weight. But I can tell you if all you're going to have is close to 400hp on tap, you don't need it (assuming you aren't gonna be sidestepping the clutch @ 6 grand)

IF SETUP PROPERLY, I.E. not to much slack, you won't break the 8.75. And for a sure grip, posi, whatever ya wanna call it, use one of those lockers. A buddy runs one in his Maxi with NO issues, and it runs 12 flat at about 115.

One last thing. I used to run 3.91s in my 69 Bee. It was a 741 case out of (of all things) a 70 340 4 speed Duster. The 741 is supposed to be weak, but I couldn't break it either. Course the car was "only" 3610lbs empty and ran [email protected] on ProTracs.