{TAIL ~ The upper endges} 451 of the right and left receiving members 481 and 491 of a generally U shaped cross section of {HEAD ~ retaining side covers} 34 and 35 are fixedly received in the grooves 411 and 421  
{ TAIL ~ The upper endges } 451 of the right and left receiving members 481 and 491 of a generally U shaped cross section of { HEAD ~ retaining side covers } 34 and 35 are fixedly received in the grooves 411 and 421
TAIL 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 HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH