SM420 4-speed and 3.55 rear in my Suburban (torque-tube). Very nice ride/power at all speeds (261 now, but was satisfactory with the 235).

I also have a 235 and Hydra-Matic 4-speed (1:1 in high gear) that now has a 3.55 rear (torque-tube). It drove fine at 55-60 mph on Interstates.

Radial truck tires on original 6.50x16" wheels/rims.