Danny Stereo, is there a date stamp hiding in the shadows there on that the chart. I can’t see one, but it is dark to that one side there... The power transformer has a date code for the 42nd week of 1961.ir is possible but perhaps not likely that the amp was built in 1961. The tube chart date would be definitive if it were there. One could check all date codes on pots, chassis, etc...but you may never know the year or month of actual manufacture for the amp without The tube chart date. The serial number can usually tell us when the amp was built unless the number falls on the cusp of a year change. You can check your serial number against this data base.... http://www.ggjaguar.com/fendamp5.htm I am not sure that I understand why someone would use a dummy plug in the shorting (main) speaker jack and the. Run a speaker off of the extension jack???? Of course, many people do strange things...but the Fender OT’s are not multitap and running one of them the way described simply uses a dummie 0lug and two jacks to achieve what could be achieved by plugging the one speaker can directly into the main jack. One of these amps should never be run with nothing plugged into the shorting/main jack.