A '42 3/4-ton would use the same 6-lug rear drums as a half ton, as the 8-lug rear-end wasn't used until 1946. Does yours have 2 small screws holding the drum to the axle? Or a couple thin sheetmetal "speed nuts" that push over the studs and retain the drums? If no to these, then tapping and prying are in order after the shoes are backed off. Tap with a hammer mostly right around the center hole and the studs, not the outside of the drum. May require some heat applied around the center hole.
