Using the VIN that you provided, I went to the American Classics web site (see link above) to their VIN decoder; according to them, your truck is a 49 1-ton (3800) built in Oakland, CA in July 1949. It's either a 3808 or 3809 (since it has a platform bed) with a GVW rating of 8800 lbs and was production number 1844 or the 844th 3800 built for the 1949 model year. Since it's rated at 8800 lbs, it originally had dual rear wheels according to the truck data book that I have. The maximum GVW for single wheel 3800s was 6700 lbs.
But to ensure that's the case for your current situation, you need to check the serial number on the rear axle; if it starts with a "SA" or "SB" it originally had dual rear wheels and hence had 18-inch rims/tires, if it starts with a "SC" or "SD" it had a single rear wheel and had 17-inch rims/tires. If it starts with something else the axle probably has been replaced. In my case, the axle serial number started with "RA" and was determined to be made in '48 but it was consistent with a dual rear wheel axle. My truck was built in the earlier part of the '49 production year so they probably used a left over axle from the '48 production run or the axle manufacturer used a calendar year for their serial numbers instead of the model year that Chevy used (my guess). My 18-inch rims have an 8 bolt, 6.5-inch bolt pattern with an approximately (this one is from memory) 4.5-inch center hole.
Also, the original brake drums (which I'm very confidant about) that are still on it are 14-inch inside diameter. If you have 16-inch rims that fit over the drums, it would seem that someone has at least changed the drums (something that seems to be pretty difficult from what I've found) if not the whole axle (something I was considering since I was having problems finding the original brake parts - since resolved). One other consideration might be that the 16-inch rims I tried to use were tubeless; if your 16-inch rims are tube-type, they may be able to fit over the original drum (I haven't tried that combination so that would be a guess on my part).
If anyone has better information than I've found; please correct me as I'm still relatively new at this.
Sorry for the long winded response and I hope this helps clarify the situation and not muddy the waters. Feel free to contact me directly if I can help.
Jim
