These photos where sent in by Tim Johnson - thanks for sharing!
Two shots of the 1972 Polaris X-3. Lez Pinz currently has this beauty.

Brad Hulings on 1982
Karpick Special Ski-Doo

(Thanks to Pat Zeltinger for the clarification!)
Ski-Doo's 4 engine entry to try for the fastest sled of 1972.