Hi, all,
Thank you for the positive comments about the posts on the LO&S motorcar. If more on the prototype interests you, the best source is the book on the LO&S, LITTLE OLD & SLOW authored by the late Ben Kline. Last time I was in the gift shop at the RR Museum of PA (where Kline was a curator) they had copies of the book for sale. The gearing arrangement I mentioned was noted but I don't recall there is much surviving historical detail on it and I believe it was not a mechanical success.
RE the model, the mechanism I used was from a KEYSTONE GE 44-ton diesel kit. The trucks/geartowers were from NWSL and relatively easy to slim down from standard to 3-ft gauge. They run very smoothly and reliably. These kits have long been out of production but they show up reasonably often on Ebay. The carbody is a narrowed-down MDC Overton combine; the curved front end was scratch-built by wrapping a piece of Evergreen scribed styrene siding about a wood dowel with rubber bands and soaking it in almost boiling water for a brief time until the styrene softens and holds the curve. This model is now about 25 years old and has been a good runner the whole time. For a scratch-built or kit-bashed n.g. motor car I would highly recommend the Keystone engine as a starting point.
George Pierson