The side walls 47, 38 are parallel with each other and have {HEAD ~ a pair} of {TAIL ~ holes} 49 formed in them to allow a bolt 45 to pass through them 
The side walls 47 , 38 are parallel with each other and have { HEAD ~ a pair } of { TAIL ~ holes } 49 formed in them to allow a bolt 45 to pass through them
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH