I just found a Gibson GA-20 at a garage sale. Really lucky find. This amp appears completely original. A little rough around the edges but still has the Jensen Alnico speaker with serial number 220106, which I gather means it is a 1951 amp(?). From what I read online, the first three numbers (220) indicate the brand, Jensen, the 4th number (1) indicates the last number of the year, 1951, and the last two are the week of the year. All three pots have a code that appears to be EG B 6150689 105. Looks like everything is original on the chassis but there are some loose wires where connections appear to have been broken. The power chord is intact and in good condition. Still has the original chicken head knobs. Missing the G badge on the front of the amp and also missing the leather handle. Anyone have any info about dating this amp? I can't see a serial number on the chassis. I have heard that Gibson serial numbers are less reliable than codes on components though. Anyone have pics of the chassis? Can't wait to get this thing up and running.