Good find @RoyBoy, although as you said very expensive. And at 63mm wide by 50mm long plus the exising motor, it might also be too big to fit.
The Williams 773 copy is crippled by what IMO is a ridiculous gear ratio, about 9:1 with HUGE driving wheels. No easy way to change it, either. Heavy weight and FOUR rubber tires create drag and a lot of slowdown on anything but the broadest curves. For the last 30 years I've been looking for toy trains that run like scale models. This is a scale (sized) model that runs like a toy train. As they used to say in Philly, "roof it!"
