Here are the serial number schemes from 1951 to 1970.
Fender bassman cabinet serial numbers.
From 1952 through the spring of 1954 fender produced approximately 660 model 5b6 bassman amplifiers serial numbers 0001 0660.
1970 1989 most amps do not have a date code stamped on the tube location chart.
These numbers always begin with eia 606 and are followed by three or four digits in various combinations.
Therefore if you have a push pull pot your amp is 1974 or newer.
If you are unable to find the production stamp find the serial number that is also printed on the tube chart.
If three digits are present the first digit refers to the year i e a 7 would mean 1967.
1951 bm00001 to bm00550 1956 bm00550 to bm01200 1957 bm01200 to bm01600.
These codes are for amps with the serial number beginning with a letter.
It does give info on dating fender amps by serial number.
If four digits are present the first two digits refer to the year i e a 66 would mean 1966.
The site gives info about amps with i e.
How about those rarebird vibroverbs.
I got this one.
1951 to 1954 the serial numbers were 001 0900.
Citation needed the earlier cabinets have been called tv front designs 1 with a front panel that had a rectangular grill cloth with rounded corners and looked much like a television of that era.