Took these pictures, and measured the dimensions for the folks over on NGRM-Online and RMweb. If you're going to show these on other forums, please link back to this blog when doing so.

Total Length: 98mm (137 including couplings)

Total Width: 34mm (39mm including cranks and rods)

Total Height: 44mm

End of wheel to end of wheel: 58mm

Axle to axle: 44mm

Please note that they are approximate, although as accurate as I can get them.

Pictures of the chassis:

Jack

Source