Bubba, there are some differences in an NOS (Aurora) and an AW chassis, which I'm sure is why he's looking for one.
Try going to Jags. They use to sell all the parts. When I bought two that way, I got the chassis and gear plates for around 5 bux each. There is one other place too, as soon as I can remember it I'll let you know.
Ron (Bondo) :dude:
Also try Slotcar Johnnie or Slot Car Central. Another place to try (if you don't mind a drive) would be to hit the Midwest Slotcar Show. Both 'stores' along with Bud's HO set up at this show and the shipping you'd pay would go for admission and gas money to get there. Plus you can get a deal much easier-face to-face.
I have successfully transplanted everything including the whole top plate w/arm from an AW 4 gear chassis to an Aurora Specialty chassis base. Everything fit with no modifications. Tubtrack aka SlotCar Central sells NOS Specialty chassis bases. That's prolly your best bet.
I have found the magnets to be a little too snug for my liking, so I have sanded them down just enough to slide in easily. everything else fits well. I have been using original bottoms to the chassis for the rails because I think just chopping the mounting ears off the AW chassis makes them some what weak and looks kind of silly..