{HEAD ~ a single, removable plate} that is detachably mounted on {TAIL ~ the yoke} in a selected one of first and second positions by invertibly repositioning said removable plate 
{ HEAD ~ a single , removable plate } that is detachably mounted on { TAIL ~ the yoke } in a selected one of first and second positions by invertibly repositioning said removable plate
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH