Bill,
If I read the VIN number correctly, my 66 GMC was number 278 off the model 5500 line, so GMC might have still been figuring out what to put on it.
I had to drive the truck to the nearest California Highway Patrol office for a VIN check yesterday, which became a real test of driving skills at stop signs and traffic lights because the truck still dies at idle (more work needed on the carburetor and ignition system), the parking brake was still too loose, and all of the intersections seemed to be on hills. That done, I had to go twice to a Department of Motor Vehicles office today (using my much newer car) to get the truck registered. First, for DMV to determine that it really exists, despite my pink slip and VIN check, and then to provide pictures for an Agricultural License application. I am now the registered owner (finally) and have a temporary operating permit while the vehicle registration bureaucracy makes up its mind about the proper paperwork. The people at DMV were nice when I finally got to talk to someone, but I think this is not really finished yet.
Thanks to everyone for the help. It is probably time to put this thread to bed and start over when I have something else to ask about or report on.