two spacer blocks spaced from one another and each said {TAIL ~ block} attached to the forward surface of said {HEAD ~ main receiving tube}, 
two spacer blocks spaced from one another and each said { TAIL ~ block } attached to the forward surface of said { HEAD ~ main receiving tube } ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH