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