{TAIL ~ Key way} 4 opens to its front end at front face 6 of housing 2 and is blind or closed at opposite end 7 of {HEAD ~ housing} 2 
{ TAIL ~ Key way } 4 opens to its front end at front face 6 of housing 2 and is blind or closed at opposite end 7 of { HEAD ~ housing } 2
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH