I recently removed some 20 amp single pole breakers from an industrial/office building panel. They are listed as being manufactured by “Trumbull Electric Manufacturing Company, A General Electric Organization”. It does not show a model number or type. It is 6 inches tall by 3.5 inches deep by 1 3/8 inches wide. The patents listed on the side all date back to about 1936. The only other label refers to it as “Issue J*964”. I'd like to find a double pole 30 amp breaker to replace the two single poles. What can anyone tell me?

There are a couple of 3 pole 30 Trumbles here.
http://www.swgr.com/products/MCCB_Inv_TRUMBULL.asp

I would just do an internet search for used breakers.