4D55/4D56 Head Differences

Bought an '83 50 with the 4D55T. Previous owner claimed it has the 4D56 head. Valve hung up and ruined the cam so I pulled the head. Has the tappet rockers, not the rollers. Just wondering what the visible differences are between the two heads so I can tell which head it actually has?

The head alone, the only thing i know thats different is the injector thread size. Only thing else is they come with roller rockers