US Trac is the direct descendant of the WWII Clark Airborne tractor (and the "father" of the ATC line, and therefore "granddad" of the Case crawlers) having been made from left over Clark parts at war's end, with the exception of a change from the Clark Waukesha engine (IXB?) to a Continental F124 industrial, blade lift cylinder changes, hood configuration, and cylinder mounting tower access hole shape. There are probably a number of other subtle changes. I have parts lists (circa 1951?) which cross reference Clark/US Trac parts, with higher prices usually being listed for the Clark parts. A gentleman (county historian) recounted his memories of working in establishing the US Trac plant in Warren OH during his college breaks in the late '40s early '50s. At some point around the ATC buyout he said the building was sold to Packard Electric for wire production and he helped load rail gondolas with much US Trac property, including parts in process, machining equipment, spare parts, engines, etc., (for scrap) as Packard wanted a "broom clean" facility.
I have seen remains of what appeared to be 1 factory made loader version, and 1 angle blade version of the basic 10A; both are listed as "upcoming improvements" in my literature. Also the brochure I have specs the Continental engine, but the publicity photo on the leaflet is clearly of the Waukesha.
It is an interesting piece of history, and spins back even further to Federated Machine and Welding, a Cleveland company that developed machines and techniques for welding tank armor for the government.
I have never found any link to Caterpillar in my several years of research on this company; however the engine was used in numerous forklifts over the years and your's MAY be a CAT transplant.
Machine s/n should be on a brass tag forward of the base of the shift tower (all I've seen are 4 digit with 50 or 51 as the first 2 digits), early ones with Clark blades will have a large brass plate on the back of the blade stating LaPlante-Choate, with some other info. There should also be a tag on the reverser case cover with clutch adjusting instructions.
I have heard of, but never seen, a machine manual-I use the Clark CA-1 manual for all but the engine and a Continental F industrial series manual for the engine, not perfect, but adequate.
