I now have sets for Tomy, Tyco and X-traction. the Tyco rears will fit any 1.5mm axle, and the XT/Tomy ones any 1.6mm axle. All three front types are for 1.2mm axles and therefore interchangable.
The rears are all a tight fit, so a wheel press is a good idea. I also found placing the wheel on piece of cloth for protection and then using a pin hammer gently did the trick. Next time I mount some I'm going to remove the crown gear as it makes things akward, press the wheels on, and then pull apart and rebuild. Or I might try and find some 1.5mm and 1.6mm rod to press through the wheels and save stripping axles.
I'm not quite ready to sell these yet, working out the final details. Who wants to see pictures?