What parts are you referring to that you'd need drawings to make parts from?
Pretty much everything is plate steel. There are few, if any, machined parts on my machine that I can think of. The engines are made by other vendors. The pumps, hydraulic motors, hoses, fittings, etc... are made by other vendors. I think they make their own hydraulic cylinders. The brake tender on the larger units are made by them as I recall. But really, I think as long as they're in business, they can support legacy machines. I can't recall anyone on here with old machines reporting PT won't support them. The might have to adapt something newer to an older machine, but it can be done. Only limit is your wallet, I suspect.