I have a Marshall Super Bass 100W amp (American Version) I've had since brand new... I had always thought it was made in 1969 tho I'm not sure...
On the Paper tag on top of the chassis it says:
"Assembly" --> Job M No 81
"A.C" --> Andy
"Tag Board" --> Joyce H
"Back Panel" --> l k
"Tested" --> T-20-69 (the T could be a 1, not sure)
Serial Number: SB/A 2231A
With the serial number 2231A your amplifier was manufactured in 1969-70.
Thanks for the help...