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