I've got a Sun 1020 (about 1970 vintage) in my shop. I think everything works, but I've only dabbled with hooking it up to a couple older vehicles. I don't have a manual so I am really just guessing. I use the lower cabinet for tool storage for bulkier items like battery chargers, etc.
It looks pretty cool, and I get lots of comments on it. It fits in nicely with other vintage items in my shop. Although they're not worth much right now, I'll hold onto mine for another 20 years or so. Since so many of them are currently being scrapped, it might be worth something by then if there aren't many left.