Just bought a 1931 Desoto, the serial number on the registration is 3A17410. I can't find anything with that number. Is it possible the number is a body style or engine serial number?
This is way out of my league, but here is some info that might help.
Before 1954 there was no uniform VIN number used in the USA.
In the years leading up to 1931 Chrysler Corp and a few other car companies used a FEDCO plate on the dash or firewall for the serial number ID of the car. The car was registered by this number by some states, and some used the engine number. Starting in 1931 the serial number was changed and moved to the door post. So a 1930 car should not have a plate on the door post.
The engine number was always stamped on the block. Also keep in mind 1931 Chrysler products were carried over into the 1932 model year, including Desoto.
The serial number depended on the make and model unlike cars of today. A series 31 model started with a number 6 or 8, while a series 32 model started with letters like SA or CFS, a series K started with the letter K, and so on. Actual serial numbers were seven digits.
On most models the serial number is also stamped on the frame near the front spring support.
You can do an internet search for DeSoto FEDCO numbers and serial numbers to get a general idea of how the serial numbers were arranged. You can also contact Chrysler Historical Society to see if they have the build card for your car. The build card would have both the original engine number and serial number. There are other resources including the Antique Auto Club of America.