Yes, it's stainless. The only thing I've been able to think of was food-related as well, but my family's never had anything to do with a restaurant and we've never been junk collectors.
There are a couple of milk cans, so I suppose that's a possibility. I hadn't thought of that, but it doesn't look nearly old enough to have been used with them. Motorcycle jack is a pretty neat theory and makes sense now that I look at it, however there's no way that I've seen to lock the tray in the raised position.
I had forgotten until just now when I looked at a bad pic of the back of it, but here's the kicker: there's no crank to turn the shaft on top.
