AS the Galion data plate indicates that your machine is most likely a 118C, and that the engine is a Cummins, you probably have a H743C-135 engine.
743 cubic inch, construction equipment configuration, 2 valves per cylinder, 135hp.
Does your engine have 2 fuel lines going to the right hand side of the cylinder heads for each cylinder? Does it have 3 separate cylinder heads? Are the exhaust and inlet manifolds both on the left hand side of the engine?
Parts are available, mostly aftermarket, as Cummins (in Australia at least) does not support this engine any more because it is old. The H743 engine, below the heads, shares many, but not all, parts with the NH220 engine. The NH series have 4 valves per cylinder instead of the H's 2 valves. You can use NH220 piston and liner kits BUT, the top of the liner has to have reliefs machined to allow clearance for the valves to open. The heads of the valves on the 2-valve H series engines overlap the top of the liner, whereas the NH 4-valve arrangement all fits within the bore. The machining is relatively simple and allows use of easily modified NH liners if H series liners are not available.
Please note: I am not an expert on this topic. I am just a guy with an interest, and a small amount of experience, in heavy equipment. Please check the facts before you act on any of my advice. I was involved in the rebuild of a H743C in a 118C recently.
Just trying to help.