Once a first extension link is selected, {TAIL ~ the first end} of the first tailgate support may be connected to {HEAD ~ the first extension link} 
Once a first extension link is selected , { TAIL ~ the first end } of the first tailgate support may be connected to { HEAD ~ the first extension link }
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD