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