When did Chevrolet move the casing numbers from near the fuel pump to the location shown in tclederman's link? Was it with the other changes from the the 1954-55.1 engine?
Here are the casing number locaions on a 1954 261. I also have a later 261 that has the numbers shown in tclederman's link. If the block is a replacement block from Chevrolet, neither the serial number (as mentioned above) or the casting number is 100% proof of identification. I have a 1954 261 block (shown in the link above) that has a 235 casting number and no "Captain's bars." The block was purchased new from Chevrolet by the previous owner.
