way long ago when our cars were new---SAE engineers liked to test and break stuff----they rated the 8 3/4 at 500 hp the ford 9" rated at 450 hp-----yes the after market chased the 9 and the SBC offering all kinds of goodies and competition kept the price down-----really nothing wrong with what you have------the engineers had bad marks on the 9 for the pinion gear being so low on the ring gear because that is the weakest spot------8 3/4 dana 44 dana 60 pinion gear located in a stronger position.....
Seems like the lower pinion gear location also results in higher horsepower consumption too?
The 9" Ford came out in about 1957 with several mechanical upgrades over the years. Number of axle splines, etc. They were "common" and somewhat inexpensive back before the huge aftermarket developed HD parts for them. That was Ford's "one axle" that was under almost all of their cars and 1/2-ton pickups for decades (with different axle housings for the different cars they later came in).
Allegedly, a Chryler 8.75" axle will stand up to manual trans shockloads if they are set-up a bit tighter than normal? Almost to the extent of the Dana 60?