850 Interstate side panels differ

Dumb question here from a newb....I have seen pictures of two different types of side panels on 850 Interstates of various years, including both types with the "Electric Start" decal on the ES models. One type is more angular and follows behind the slanted back frame tube. The other type is more "squarish", and covers the slanted back frame tube. Why are there two different types of side panels, and what year did they start, or stop?
Thanks for your patience.

singring said:

One type is more angular and follows behind the slanted back frame tube.

Click to expand...

That is actually the Roadster or Hi-Rider model panel.

http://www.nortonmotors.de/ANIL/NCRoadster.htm
http://www.nortonmotors.de/ANIL/NCHiRider.htm

singring said:

The other type is more "squarish", and covers the slanted back frame tube. Why are there two different types of side panels, and what year did they start, or stop?

Click to expand...

That IS the Interstate panel.
http://www.nortonmotors.de/ANIL/NCInterstate.htm

There were varous detail changes made to both Roadster/HiRider and Interstate panels over the years, as some were steel, others were glass fibre/fiberglass and the fitting arrangements and colours also varied between models. Many owners have swapped tanks and panels around, so it isn't uncommon to see a Commando fitted with an Interstate tank and Roadster side panels, for instance.

There were three "styles" of Interstate primary side panel and one style of interstate oil tank cover. This is in addition to the fiberglass or steel substrate. All have the same basic shape.

The "standard" 750-850 primary side cover has the fastening Dzus clip on the tab that connects to the button on the frame under the tank. The MkIIA has the Dzus button in the lower right corner of the panel and the MkIII has the Dzus buton on the top of the panel fitting into the clip on the plastic air box.