I've seen at least 3 different wheel/axle combinations under '73 D22s like mine. I doubt there was any greater consistency on the '72s. I could very easily be wrong, but my money says you'll need to ask around to find a capable tire shop or truck shop to take the rig to & get some advice from an experienced, trustworthy mechanic. Good luck trying to figure out which is which. My experience is that the independent shops have a wider knowedge base, especially if you get the guy whose been there the longest.