i recently purchased a rebuilt head for a 1994 honda civic dx 1.5 16valve.like a dumbass i turned my core in before checking it with the new head.well it was the wrong head the casting numbers on the old head were pm9-2 and the new head pm9-3.every web site i go to to try to find the pm9-2 it doesn't list that casting number anyone know why i can't find this head?