Go here for what's to know about vitnage FEnders.
That 'Fender Elec. Inst.'---FEI--indicates pre-CBS. BF FAceplates from the CBS era...started in Jan 1965....read Fender Musical Instruments---FMI-- in that spot. The tube chart in that amp should have stamped dates codes reading 'M-', 'N-', or possible early 'O-'.....M would indicate 1963 and would be a very rare amp, N is 1964 while O would indicate 1965. A 1965 amp coudl possibly have a FEI plate as a transition oddity. NOte: the second letter of those dates codes would indicate the month....A = January,
B = FEb, etc.
Teh transformer codes are visible from the back of the amp as are the speaker codes unless the speaker codes are covered by thelabels on thespeakers. Ime, the tranny codes are not enough info for me unless Iknow the amp and or the owner already. I have seen exc cond BF amps with all codes that are visible on the outside look like they were top dollar amps. When the chassis was pulled, both amps showed massive gutting...all components on the boards were changed as were all of the pots on the front panel. This reduces value by at least 50% from exc orign cond values, imho.