who makes this air tank?

It looks exactly like the tank fitted to my Revell "Master Class" compressor;

The compressor complete in comes @ about £175.00, it is a rebranded Sparmax compressor. I could be wrong here, but I would think trying to get a new tank for the compressor may not be cost effective. I think your best bet would be to have it repaired on the side by a fabricator / fitter, as the tank appears to have a flange around the damaged thread - this could be cleaned out & an insert fitted to make it "good as new".

Find someplace that can weld a new one on for you. They probably can place it right on top of the existing one. Check with the local auto body repair boys...they might do it for a couple pints of their favorite beer.

Just be sure the weld is correct as it takes a good welder to weld an air tank and keep it safe if you are putting much pressure in it.