I installed a hydramatic in my 54 going from 3 speed on the column. More differences in 54 than you might think. The frame was even different as the Hydramatic had heavier crossmembers that unbolted so trans could be removed from bottom of truck. Brake lines routed differently for same reason. Trans cover different for access to bellhousing bolts, Driveshaft different length, starter different for solenoid start instead of foot stomper. Pushbutton start switch. Carb different due to electric choke instead of manual choke. Shift mechanism obviously different, linkage different, There was a new neutral start switch with detent bracket. I found a pretty complete rolling chassis for hydramatic, collected the missing pieces, and built new frame to put truck body over onto it. I kept manual choke as I have dual carb intake and cut the floorboard to fit the new trans cover. Just make sure you know what the project involves before you get too buried in it. All that being said, I would never consider switching back. It is nice!
