This US Pipe locomotive is a Plymouth Model W (3 axles), with - apparently - no roadnumber. This little engine, weighing 25 to 35 tons, was at some point re-engined with a Caterpillar prime mover. This "critter" appeared to be out of service when it was photographed in April 1981 in Irwindale, California. Thanks to Bob Graham for the background on this engine!