jake,
d2 axles would be an obvious choice, until you figure a p38's frame is wider. the rear has a pan hard, which is better than a watts, but means you really need to modify the axles, then 'make' some radius arms, front and rear. keep in mind the arms would be tricky, because they would also need to correct pinion, wheel base, and bent to mate with the d2 axles.
I'm thinking the pumpkins being on the other side would be a set back too
The question was.. is it possible to run an lt230 and D2 axles on a p38. Obviously a lot of fab work but may be the only way to get cdl