The crossbar track and the rubber track have different diameter rear wheels. The replacement track kit for the rubber track came with the larger diameter rear wheels and an extra pair of wheels that would be mounted mid-skid. I may have the instruction sheet for that swap somewhere.
But, with that said, if you are using the wheels from the Intruder and the track from the Intruder, they should match up and work fine.
When you talk about front idler wheels are you talking about the drive shaft?