Ike you are right on about the V-Max 540's being around until 1991. As for this STX model in Canada that I keep hearing was only sold here and no where else. I hope to get more information on it so hopefully by posting these photos it will get people talking. I had herd of it when I was younger but never seen one until this week at my friends house.
I will be talking to my buddy soon and I will ask him more about this sleds history. He said in the mid 70's Yamaha had a good engine that was strong and fast.