[jocko]

the purpose of air shocks (other than to jack up your 57 chevy in high school, which I did) is to have handy (debatable) and adjustable compensation for heavy loads that you may carry on otherwise stock springs. In other words, if you often carry heavy loads, air shocks would give you the option to add more air pressure to prevent sagging under heavy load (or towing, for example). Air bags inside the springs do the same thing.

blackedoutharley is correct - it IS counterintuitive, but it does serve a corner-case purpose. And if you use them, your ride will pretty much suck if you keep air in them. If you don't, then there's no reason to have them.

for our trucks, unless you're hauling a bed full of bricks every week or towing a trailer, recommend a good set of shocks like blackedoutharley mentioned - monroe/gabriel/kyb, etc. kyb a bit more expensive. Put Monroes on my newer truck today in fact.

Bottom line, above all - DON'T attempt to restore those shocks, and unless you're doing a good bit of towing/heavy hauling, don't even bother with air shocks. (and frankly - even if I were, I'd use air bags inside the coil spring to minimize sag with stock shocks anyway - that way when you deflate the air bags when not under a heavy load, you still have an actual shock response to road bumps, etc)

as for originality - not sure if they were available, but i seriously doubt those are original even if they were. they don't last forever - and those look kinda like monroe skyjackers to me with the faded yellow paint.
Could also be Gabriel I believe. Hey, maybe they ARE the shocks off my ol 57 from back in the day.... I'm sure they made it into some yard sale down the road from the last time I saw them.
my 2 cents!