I have a Moser Dana 60 under my hemicuda. Put it in there in 2003 after grenading the 8.75 running mid 10s at 3700 lbs. The car ran mid 9s starting in 2006 and now it's a little faster...would like to see 8s soon.
I've had the rear cover off once...last fall. Just to change the gear oil b/c I realized it had been 10 years.
My car is over 3800 lbs, drag radials, leaf springs, footbraking, etc.
Back in '03 I think I paid about $1800 for the Moser 60. 35 spline axles, spool, 4.10 gear.

The dana gets the nod for my cars for cost versus strength. I built a dana 60 for my dad's '69 road runner. Less than a grand in the whole thing...35 spline axles, powerlock diff, 1350 yoke, etc. Built it from a junkyard truck rear.

If I was starting from scratch and building a FAST car, I'd go w/ a 9". Less weight, VERY strong, and any gear ratio imaginable is available. I would start w/ an aftermarket fabbed housing and big bolt through aluminum case. It wouldn't be cheap, but you'd have one heck of a rear.