Jerry Branch ironheads have a small number stamped on the bottom near the intake port. This helped identify your heads when you sent them to be ported and flowed. At swap meets, I find myself looking for these numbers - even before looking at the ports - or what the heads fit. I've never found a set yet . . . and I've looked at hundreds of heads. If you ever see the beautiful porting on a set of these, you'll say - Wow !