My truck is a 46 half ton, but, CPP has a 6 lug conversion kit. Also, I am going to a modern rim because of the clearance associated with the original rims. I have 16" rims and they do not clear the calipers due to the corners that are present in the back of the rim from the center section. And talking to several tire folk, the modern tires can have issues seating on the older narrower rims.

"it's only old if you can't find a use for it; otherwise it's cool and i'll use it."