Schwinn made 20" cantilever frames for many years before the Stingray, and confusingly, also made a 20" Spitfire in the '60s that was essentially a Jr. Stingray with the 7-hole crank. What I've run across a lot recently is Stingray frames modded up with late 70s BMX parts. I love seeing the efforts of kid mechanics, some of the combinations of stuff are pretty wild.