The reason I pulled the head was the compression on #1 was 340 psi and #2 had 300 psi. It ran okay for awhile, then started belching out some grey then black smoke. Anyway, I'm replacing pistons, liners, rod bearings, & the necessary gaskets. Once again, this tractor was left on my property by my brother, I don't know the history. We don't speak. This was given to him as some kind of a barter deal. The #2 piston was damaged on top where the air intake is, just a wild guess, but I'm thinking someone used starting fluid. The rings on that piston were broken. #1 had one broken ring, and the piston skirt was scuffed pretty good. As far as a Viet Nam rebuild, I don't know. The research I've done shows this head is for the ym1800, and looking at the picture (I know, hokey) of the ym1800 head gasket it has the same hole pattern as the one on the ym240 head gasket. I know there are no easy answers, but a new head at this time isn't feasible. jbrd