Just follow the Manco line and look at sears catalogs, Its pretty easy. Manco (at least thier Karts) didnt start to even show up in sears catalogs til 1976 and they were using the sprung seat trailcat for the next couple of years. 1979 catalogs show the start of the "speed Hole" reinforcement bikes, Again I don't know the names or if they even had any in the sears catalogs. This also matches the Manco line being sold at the same time, the small bike of course was the first "streaker" and the larger full suspension was called "screamer" which was a name they used in the past. that design ran until 1982. both the sears and Manco catalogs in 1982 show the major design changes which did not include the "speed holes" The sears version at that point was called "green streak"....and yes it was green, The Manco version went Red and was called "SXT"