O ring 109 seals against fluid leakage between {HEAD ~ retainer plate} 104 and {TAIL ~ rear cover} 89 
O ring 109 seals against fluid leakage between { HEAD ~ retainer plate } 104 and { TAIL ~ rear cover } 89
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH