Alot of serial number listings on the internet just summarize all of the prefixes by year. If one goes back to the original Specifications Guide one can find the 'Application' codes for the heavier and long wheel base trucks:
tocmp: 1946 Truck Specifications So a BM is a 216ci truck engine for a 3100 series built in Tonawanda. But the Year is missing . . . e.g. DBM - '46, EBM - '47 , FBM - '48 etc.
stock,
You gave me a piece of the puzzle there and I have to admit I missed it...however, it doesn't seem that J coincides with '53, and mine is a JBM on the serial number...that seems to give me '52. My stamp on the block is K303, and it's odd that the J is there on the serial number. Yes, this makes sense and bursts my bubble on the Corvette block, possibly.
Since it has a newer head it must be '53 as the block casting date, the later part of '53 is when that changed. And since mine is November, that seems to make sense. J is an interesting oddity on my engine block.
