Do they offer the set with or without the head gasket.. I ordered a set but assumed it was without the head gasket and ordered it separately but the set came with one... and I've got a set for my 25 and 20 hp and the set came with everything minus the head gasket... well I assumed the 6 hp would come with everything also but it was missing the oil ring for the bottom crank seal and the top oil seal... so are those not included??