Lioneltin- The rear driver axle has the gear for the worm drive and has the lip on the wheels to secure the tire. I'd have to pull the drivers and change axles to do the switch, but I gotta tell you, I think you're logic is spot on!
"Those two things you called rivets go exactly were you thought they did" - Too funny Jim! Thanks for reassuring my guess work! I was wondering if they were just track droppings that got sucked up via the magnetic field!
Rich
