A rearend that I thought about finding for my 37 was a 41-2 3/4 ton rear,open drive shaft six lugs. Supposed to be same width as the 37 which should be about the same for a 31,but still a ancient rear,probably steeper gears than a half ton. I gave up tring to keep my 37 six lugs,modern rims are available to run the old style hub caps and they are not too expensive. You are not serious about running bias ply tires,I would not wish them on my worst enemy as those tires are terrible compared to radials. I would have better handling than for old time looks unless you dont plan on going too fast or far. I am using radials on the 15 inch artillery wheels and had no problems yet,went tubeless also with no air leakage.
