{HEAD ~ means} for detachably mounting said hopper box across the rear of {TAIL ~ a sand/salt hopper truck} 
{ HEAD ~ means } for detachably mounting said hopper box across the rear of { TAIL ~ a sand / salt hopper truck }
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL