Up through the early 50's a number of states used the serial number that was stamped on the engine on a pad near the distributor as the vehicle's vin number. There is info on the serial numbers here.
http://chevy.oldcarmanualproject.com...gine.htm#53eng
I was living in McGregor, Tx when I bought the 48 in 1973 and the previous owner being a stickler for detail had applied for and received an "engine change title" that used the number on the door post.
If the Vin number on the title matches the number on the tag on the door post you are home free. I
f it matches the engine and you have the old engine with that number stamped in it don't get rid of it until you get the title corrected. I'm not sure what the process involves but it should be pretty simple.
If truck didn't have an engine or came with a different engine and has the engine number on the title I'd register it that way and at a later date go in and apply for an engine change title.
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