The issue is this lift is a 1957 model. Yale & Towne, now Yale, now owned by Hyster, has gone through multiple ownership changes. Dealers and even Hyster aren't going to have any records. Most can't even identify part numbers. This isn't unique to Hyster. If you work on old equipment and brands have gone through multiple owners, perhaps moved, or been consolidated. Finding information is like finding a needle in a haystack. I can fill in the data specific to this lift from what is visible and what is in the owner's manual. It's the more generic model data that is missing (shift pattern, safety instructions, etc.)

You need to get in touch with dealer and give serial number just because same model doesn't mean same unit