Frank -- When I needed to put a value on my truck, the first place I went was Hemmings Motor News to see what similar trucks were being priced at. Even though there weren't any *exactly* like mine, there were enough that I could triangulate reasonably. I just checked and there are 46 listings for '48 to '53 3100's. Probably enough to give you a rough idea. A couple of them seem close to what you have, but I didn't open any of the ads.
Just remember that online listings are *asking* prices, not final
