I apologize that this has been asked before, but I have a 'slightly' different question regarding 8.75 vs Dana 60 rears:
The 3 factors that seem to add up to whether or not an 8.75 will survive in a car are 1) Car weight where < 3000 lbs OK, >= 3800 lbs leans toward Dana 2) Stock or slightly modified HP <= 450-475 HP OK, High HP/TQ > 500 HP again leans toward Dana and 3) Automatic better for 8.75, 4 speed leans toward needing the Dana. That's what I've been able to glean from a fairly extensive web search.
So of course I want to buck that trend with the Roadrunner because I'm seriously reconsidering how much of the original driveline to leave in the car. So it probably weighs around 3800 lbs, Stroker build I'm looking at could be as much as 550 HP & 640 TQ (found a magazine build I may try to copy that resulted in these numbers), and want to swap in a 4/5 speed for the racing automatic in the car now. Am I crazy? Can the 8.75 be made to handle this combination? I wouldn't want to weld on external bracing etc. like I've seen on some fabbed up or heavily modded 8.75 rears I've seen, looking mostly stock 70's correct is a primary design goal.
I know if I was thinking 700-800 HP it would be the Dana for sure, my combo seems to be borderline so the question is if the 8.75 can handle it then what do I need to swap out internally in the housing to make it safely handle the load? I may contact some of the vendors to see what they say, but they could tell me the 8.75 will work with mega $$$ upgrades and it still not last in my car.
Thanks in advance, Jim