Kitty Cat Snowmobiles

I just picked up a new new kittykat, well new to me, I am trying to find out what year it is, currently I know it has the kawi engine so any idea on year range??

early 70's . check to see what name is on the carb .it can help narrow it down

carb pretty dirty looks like kikaki something I guess it really needs a good cleaning. How many different carbs were there? I would like to know, I had looked for that info for example like 72 and 73 had x engine with x carb. This is an A motor from what I have read,on the engine shroud. Any one know the spec differences between the a and the b?? Any stroke or bore change?? Also from the pictures I saw It looks like I am missing the little red knob or key on the engine, It does run though, A pretty good deal, I had a friend bash my 02 legend 700 on a rock last year, spawning a NY trip for a tunnel and the smashed remains that had 2 heat exchangers pawned the deal from a local sled yard, even trade, nice