1980 was the last year for the 340 Invader. They are geared lower to make better use of the smaller motor, and thus don't have quite the top speed of the 440, but they get there a LOT quicker!! Most ice drag sleds use the 340 gears for a quicker takeoff.
My first Kawi was a 340 (1980 too) I was mighty impressed with it and that started me in getting the dreaded Mad Kawi disease...