I know they are old, and have limitations, but I'd be a novice, hack welder just starting out. I have a line on 6 white face 35s, supposedly working. Taken out of service because of age.
They are up to $20, yes $20. Unfortunately, they are a 3-4 drive north of me.
What do they take for power? Hopefully 220 single phase. You can run machine tools off a variable frequency drive if they're 3 phase, but I wouldn't mess with a 3 phase welder at home. A rotary phase converter would up the price to that of a newer machine.
If it's single phase, I'd get all of them, keep the nicest, gut a parts machine and sell the others as welders or scrap. Time aside, you can have a free, very capable welder.
The list says 480 volts. Doesn't say anything about single or 3 phase.
Some welders can be wired woe 480 (3 phase) or other voltages / single phase, but I'd say those are about a 80% chance of 3 phase only.
I had 3 phase power in the warehouse I lived in for a few years, but not anymore. I do have a 25KW 3 phase generator I could fire up if I ever get a garage set up again!