Okay,let's try the differences.
Very early models had sand-cast motors,the give-away is the positioning of the vertical ribs between the fins on the side of the cylinder head.
The so-called KO (first) models had a different airbox/side-cover configuration.
The carbs had four separate throttle cables,no cross linkage so balancing was fun and frequent,not to mention the very heavy pull.
Later models got an uprated drive chain,the earlier ones tended to part at the master-link and break the crankcases.
When did the black brake caliper start?
The list of changes goes on but those are the earliest I can remember...............
Your one seems to have an interesting front spoiler/airbrake/bug deflector/number plate.