Here's the big stumbling block, there were no 1/2 ton Napcos pre-'55, only 3/4 and 1 ton. Napco didn't produce any 1/2 ton conversions until they went to the open driveling in '55. HevyHauler has probably the best solution if you want to convert your 1/2 ton. You will have to change the transmission to one that will accept the later t-case, there may be some machining of the bellhousing required as well to make the later trans (larger bore id) to fit.
