When you consider the F2 sidecars only really arrived on the scene using TZ350 motors around the time we had all stopped running TZ350 solos, Yamaha had stopped selling complete bikes after 1981 but parts were still available to build motors, and the F2 lads went on using those motors for another 10 years or so, with plenty of parts still available.

So there should be enough 600 bits around, particularly spread over 5 different manufacturers, to see the chairs through a good few years post Supersport 600.