A 1934 photo of Ludlow & Southern No. 2, a former steam locomotive repowered with a Holt tractor gas engine, photographed at Steadman, Calif. (thank you George!)

Long before the mine gave out, the L&S’s primary locomotive, the boiler of that ex-NYC 4-6-0 picked up secondhand through a broker became incapable of safely operating. Like everything else on the railroad, the deferred maintenance of the Ten-Wheeler led to another quandary. How to get the hopper cars from the mine to Ludlow? It was only 8 miles of rail... so nothing fast and incredible was needed, but something WAS needed

It was time for creative thinking.

Besides the boiler, all the other components of the 4-6-0 were in “serviceable condition.” so they got rid of the boiler.  As well as the cab, pilot, and handrails.

In its place, a Holt Manufacturing Co. gasoline tractor engine was mounted on the frame and connected to the drivers by chain drive. A fuel tank was installed where the cab used to be, and rudimentary engine controls were mounted on a stand. 

The logic of using a Holt engine was flawless. Holt, which had already established itself as a manufacturer of tough tractors, was headquartered in Stockton, Calif., so replacement parts, if there was money on hand, were not that far away. Holt, by the way, was later absorbed by Caterpillar.

Incredibly, the contraption worked. While it could only go a few miles per hour, with a short 8-mile trip it really wasn’t much of an inconvenience. When the railroad quit, presumably the desert, or the local scrap dealer reclaimed the makeshift locomotive.

https://www.trains.com/trn/railroads/locomotives/the-oddest-of-oddball-locomotives/