that is a 1974 in Liberty Green (I think that is the color name). The 1973 Green would be Candy Bacchus Olive.
the exhaust is not original. The original headpipes are more rounded and it would be a 4-4 stock. The crash bar, fairing, and luggage, are also aftermarket pieces but other than that everything else looks original right down to the grips.
Edit: That is Freedom Green metallic, not liberty green. Sorry. Either way it is a 1974 only color. For some reason you don't see a lot of 1974s, espically painted that color.