I have a newer style track on the Intimidator and my 81' Invader. I removed the locators on the drive shaft and installed it allowing the wheels to move freely from side to side (making sure the wheels were outside the nubs when installing). Once the track is installed, I used simple hose clamps to locate the wheels. It doesn't take much to hold them in place and they don't spin on the shaft so there we don't need to worry about them wearing.
It's been several years since I have done the 81' but I do recall that the rear drive shaft needs to be lengthened. I think the first time I had a custom one made, and the last time I cut down an extra mounting shaft and re-taped the end. There are also wheels outside the rails towards the front of the suspension that need to be widened. I don't recall how I accomplished this, but I don't think it was too difficult. I can take a look later and get some pictures if you need it.