Stumbled on it and looks like a proper 500 to me. I think?
http://www.ebay.com/itm/1950-gmc-motorhome-bus-rv-/261649638591?pt=Motors_Manuals_Literature&hash=item3ceb88a4bf&vxp=mtr
Ueah, that's a 472/500, but of course he says, "I know it's a dodge big block thinks it's a 440" --- so who am I to argue. ;D A rare motor home, read, converted bus.
Keeper, why not tell your friends who are buying up every 500 they can find about this? They could yank the engine and sell the rest for scrap, which would more than cover the cost.
Interesting shorty version of a transit coach. Not many of them around when new, most were the 35' versions. Originally it would have had a 4-71 or maybe a 6-71. But the shorter versions were usually powered by the 4-71. There were gas versions, but are incredibly scarce. Of those, many were propane powered.
Mike