bobcat used the 4jb1 in the 843 and 853 skidsteer, early models. as for the glow plug, i need to fiddle with it some more, i dont want to leave it in there-its just was some folks suggested. if i were to cap it with a short bolt, i imagine that would solve the loss of compression and dirt entering, anyways. mind sharing the contact info for the marine place you got the gasket from?