i had a similar problem. the person who had the car before me said i had a 389 in my 1963 catalina, but i wanted to know the year of the motor. there are three spots where the casting codes are. on the front of the passenger side head, on the back of the motor where the distributor is, and on the intake manifold. the WE you talked about is your block type. you can look up codes on the internet, for example my motor is a YU block. also look on the side of the motor for the freeze plugs, all motors before 1967 had two plugs, and after 1967 they had three plugs. btw it turned out you dont really have to get the number by the distributor, just get the block type and the number on top of the intake manifold, then look up all the pontiac motor codes and narrow it down to which one is yours. mine turned out to be a 1974 455 motor with a 1966 tri-power setup off of a gto.