The base has been pretty well covered already. The starting point is the six inch difference in the wheelbase of the two frames ('32 - 106" and '33 - 112"). As Sheldon notes, the '32 firewall is a separate part not permanently attached to the cab while the completely different '33 firewall is an integral part of the cab. The dash are instrument panels of the two years are different, although interchangeable.
You would want a '32 bed, not a shortened '33 bed as I don't think the mounting attachments for the rear fenders would line up correctly. It is also likely that you would have to modify (or use the '32 versions of the #1 and #2 floor boards) the '33 floor boards to achieve proper clearance for the brake and clutch pedals on the '32 chassis.