Good afternoon. Is the gearing better on the 915 tranny for V8 applications. Are the heavy duty axles i purchased from renegade for the 901 useable on a 915? How about the heavy duty clutch as well. Lastly, what do 915 trannys go for? Thanks mucho!

The later 8:31 ring and pin has taller gears, but you will still want a taller 5th. 29:21 5th
A lot of money just to get 5 useable gears. And no the renegade axles won’t work with the 8:31 ring and pin but will work with the early 7:31 ring and pin 915.
Money wise... keep the 914/901 trans and just block off first gear and put in a flipped H for 5th.
Most early muscle cars were only 4 speeds anyway.

915 trans. $2,500-3k for a core. $5-8k for a proven good running or rebuilt trans. There are deals out there but they have gotten few and far between.

Best to figure out a budget and then figure out what system and parts will fit the budget.