According to "Vehicle Identification 1938-1968" which is the publication used by law enforcement and motor vehicle departments to find ID numbers, there should be no number relating to vehicle identification on Chevy truck frames from '38 through '53 (probably earlier, too, but this book starts with '38). In '54-'59 the serial number was stamped on top of the left frame rail halfway between the front of the frame and the firewall. It might be a good idea to look there to make sure it wasn't a really late '53 frame, or a misidentified '54 frame, just in case.
If 'twere me, I'd be sure that the body comes with a clear title and a proper matching number plate on the door hinge pillar, and not worry about a possible frame number. It's covered up by the fenderwells, and the DMV people are looking for the body plate anyway. Unless there is suspicion of stolen parts or a stolen truck, usually caused by title documents that don't match the body number, they'll never look for a number on the frame, especially when the book says there isn't one.
And make sure that any title issues are resolved *before* spending any serious money or doing a lot of work. I heard a story just the other day about a local guy who spent a couple of years and a bunch of money on an F-100, only to find out he couldn't get title because the truck had been involved in a messy divorce before he got it. He ended up getting things straightened out (in a devious manner) but it was a lot of trouble.
Another reason to get title resolved before starting work, at least in CA, is that CA charges tax on the value of the vehicle. Before you start work on it, it's worth a lot less, and your title documents will reflect that value as long as you own it. Technically, you're supposed to go to the DMV and fill out a form that says you have done work that increased the value of the vehicle by X dollars, so that you may have the privilege of paying more taxes, but I've never heard of anybody actually doing that and I've never heard of anybody being challenged on it.
It's a lot harder to set a low value when the DMV clerk has just done a VIN verification on a restored truck that still smells like new paint. Some of the DMV people are ignorant, but few are stupid. If you go in to take care of title and registration after you build the truck, your renewal will reflect that every year.
Joe (who used to be an independent licensed VIN Verifier for CA DMV)
