Thus, {HEAD ~ the vehicle} can be converted into {TAIL ~ either a flatbed truck} or a semi trailer truck 
converted into
Thus , { HEAD ~ the vehicle } can be converted into { TAIL ~ either a flatbed truck } or a semi trailer truck
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH