Thanks for the replys. I bought one thread adapter to use with my compression tester. If all adapters are made as this one is I would diffently see if adapters were installed in the head.
Will the head have the casted number you show in the picture if it is a Heisler head? I will have to remove the cover and check. I just got the tractor last fall and its been in the shed while I been working the mouse infested clutch. They sure can make a mess.