Cylinder head 15 may be made of {HEAD ~ aluminum} or steel in {TAIL ~ the normal manner} 
Cylinder head 15 may be made of { HEAD ~ aluminum } or steel in { TAIL ~ the normal manner }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL