You're definitely more knowledgable about this sort of thing ... the only way to really tell is to run the VIN. But the 77's had spokes, and an early airbox ... are you talking about the OP or the one that's referenced in the Craigs add by _cy_ ?
Originally Posted by bmweuro
It is defiantly a 77. Non ribbed trans case, early choke lever zip tied to a late airbox, non remote shifter, early frame..........
It looks like some was parting out a 83-84 R80RT and took the rear fender, tail light and wheels and put them on this RS.