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