Is that a -B- on the front of the passenger mount what does that mean?? I just noticed Mine has an -A- on it is this a way to tell the difference between the big block and small block K-frames? I'm getting totally confused here why do factory big block mounts in a factory small block K-frame work for some people but others it won't. My engine compartment and K-frame will be painted before I load the motor in from the top. I wasn't planning on doing a test fit before painting but now I'm thinking I better.