Adding 2 rear wheels on a backcountry 600?

[nytro4]

I have a backcountry 600 with the 2 rear wheels, I want to add either a 3 or 4 wheel setup ,to cut down on the rolling resistance this sled has, it has the 16 inch wide track, what other model skidoo can I order parts from so I get the right spacers , and needed parts to do this conversion.