Using 8 3/4 with /6

the 7 1/4 is strong i have it behind my slant six 4 speed 3.23 gears in the rain in the dirt in normal weather dumping the clutch no problems at all i did this as well to a 318 4 speed with 3.55 out back people have told me there weak i could'nt break it till this day, not unless you have a 340 360 383 then that's another case and to add these rear ends have never been rebuilt. both 4 speeds have 3.09 first gear. the only benefit i would see is the swapping of gears for long highway drives.