Holes are drilled to enable the selective coupling of {TAIL ~ a ball mount} and a lynchpin to {HEAD ~ a drop bar} 
Holes are drilled to enable the selective coupling of { TAIL ~ a ball mount } and a lynchpin to { HEAD ~ a drop bar }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD