From Steve of Ranch-Design.com:
The spur gear is included in the Adjustable Chassis Kit.The choices are 34T and 36T for the spur gear. The pinions that will work are 10T and 12T. The motors that can be used are Radio Shack, Carrera Go!, and SCX. The axle size is 3/32". It is available via www.ranch-design.com
The smallest Ranch wheel that can be used is the .395" diameter wheel due to the diameter of the spur gears. The width between the axle bushings is 1.185" so the track width can be an issue with some 1/43 cars. These chassis, as with the inline chassis, can be used for the smaller 1/32 cars as well. The wheel base adjustment goes from 2-1/4" to 3-1/4" using the front most axle hole.
