I'm not saying I know what year it was "built", but if you consider the transformer production dates to equate to the amp production date, that's just unrealistic. I've had maybe 20 Fender amps from 57-77 and invariably the transformers were made well before the amp left the factory, simply because Schumacher was not in the Fender factory! I / we see this in guitars too, and many mix up pot dates with guitar dates etc, or get upset when a body date is a couple months off a neck date. Pot dates can easily be years prior to guitar dates. What I've never seen but it could still exist, is a speaker date OLDER than transformer dates. What I typically see is speakers came last and transformers came much earlier. Still a solid chance the speaker was replaced even in 50-60yo amps with "correct" date codes on the speaker. Lots of us look for correct date code used speakers, and we also blew a lot of those barely adequate speakers made in the '60s! But with very high consistency, transformer manufacture dates are well before amp build final assembly/ shipping dates. And with similarly high consistency, various dates Fender put in amps were not tied to final assembly dates. I think we know that Fender was not putting actual final production dates on amps when they were finished, because it was just not something they valued the way we now obsess over dates. If one looked at a bunch of Fender amps with transformers from the end of '64, because Leo kept ahead on electronics parts, many or most of those amps with late '64 transformers didn't ship until early '65. The chances Schumacher made transformers in Oct/ Nov, shipped them to fender who typically had transformers in stock well ahead of using them, and Fender sold them in an amp before the end of December, is really pretty slim AFAIK?