[rotorwrench]

When the automatic transmissions and the new rotator valves came out, the 1BA designation was used for the engine block. All the blocks were the same whether 239 or 255 CID. The crank was changed in 1951 to work with the torque converter whether it was a 239 or a 255.

Pickup serial numbers have a bit more mystery in the late 40s & early 50s and especially in Canada. In the US for example, 9RC would be for a 1949 or 50 (by the first number) the R indicates a V8 and the C is the code for a 1/2-ton pickup or F1. What they used in Canada for pick up serial numbers is not a well know subject to me but they may have followed some of the practices used in the US.