In 1973, Fender removed the "Tail" from the logo.
But heres where it gets a bit odd:
022699 - 606 - 5 - 04, the fourth week of 1965
022871 - 606 - 4 - 01, the first week of 1964
And then this:
Which would date your transformer, 606-0673. The first two digits, 06, do not coincide with any particular vintage year to my knowledge. And then the last two digits, 73, obviously do not coincide with any week of the year as their are only 52 weeks in a year. Unless they're flip-flopped, the last two being the year and the first two being the week.... That'd put your amp at a '73.EIA numbers taken from the transformers may help you to determine the date of production on amps that fall between the different dating schemes. These numbers always begin with "606", and are followed by three or four digits in various combinations. If three digits are present, the first digit would refer to the year i.e. ("7" would mean 1967). If four digits are present, the first two digits refer to the year i.e. ("66" would mean 1966). The last two digits would refer to the week of the year i.e. ("26" would mean the 26th week or approximately June). An example would be: EIA 606-4-21 would mean the 21st week of 1964.
Can you put up a picture of the Fender decal?
Here is the decal from a blackface bassman, note the "Tail" off of the letter 'r'
Here is the decal from my '76 Bassman, note the "Tail" off of the 'r' is not present.
