Originally Posted by HAMPAMP TUBE AMP SERVICES

If your serial number starts with letter A,B,C etc. it's easy to date. A started in July '69 B = '70, C = '71 etc. If it is older than July '69 it is a little more difficult to find the date but you may be able to get an idea by reading date codes on the pots, transformers and caps, but then it is only an estimate since those parts could be surplus from years before the date of manufacture.