I took a look at the pics- I don't think knowing the model & serial #'s is going to help you much as these machines are old. I seriously doubt that any parts would be available thru forklift channels for these units.

I think parts would have to be sourced by matching them up, getting them made, etc. Forklifts from back then were much easier to cross to their automotive roots.

With that said, I must say though that these lifts are a liability issue. If anyone were to get hurt on these lifts I'm quite sure you'd have legal issues. I'm sure that the operational manuals which are supposed to be kept with the lifts are no longer available, the capacities have to be listed on the machines (and the tags have to come from the manufacturer), etc. My advise would be to sadly retire these units before they bite you hard (IMHO) :(