polaris 1010 is correct. The engine in your sled does not have reed valves. I have the same engine in my sled. Polaris outsourced their engines to Fuji at the time and did not start using reeds or Variable exhaust systems untill they started making the Liberty motors. But dont get me wrong, the 440 specials are fun and fast! Mine has 5000 miles on it and is a 1994, but beat my friends 2006 indy 500 many times last year in races!