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