JimC said:
kempoyner,
I believe the only differences between the Fastback, Roadster, Interstate, "S", "SS" and Hi Rider were styling changes. The frame, engine, transmission, rim size, suspension, lighting, were all the same. Maybe some models came with different tire tread pattern. Check out this link:
http://www.nortonownersclub.org/models/commando/
The FB (original Commando and later FB), Interstate, SS, and Hi Rider all had oil tanks in the side panel, the S, R and 70 Roadster had oil tanks behind the air filter, called the central oil tank, of which there were 2 models with the timed breather going into either the top hat (early) or behind the top hat (later) and the key in the right side FG panel. Pre 70 models also had a short prop stand and the centre stand mounted off a rib between the frame. After 70 the centre stand was mounted on the cradle. Fenders, seats and sheet metal were all styles associated with a particular model, although a lot of stuff overlapped. You can get a good idea looking at the sales brochures for different models. There were a lot of improvements/changes made after 70, but most stuff will fit year to year. In other words, you can make just about any model from any year you have, withing reason and given the issue of the central oil tank/fiber glass panels on the early models.
Dave
69S