Since Fender pulled stuff out of the parts bin, you're only gonna get an estimate of age AND you're not going to be 100% sure of the circuit revision without posting pics. For the date, compare:
1. Transformers 606-XYY where the X is the last digit of the year
3. The serial number stamped on the chassis
The date of manufacture will be after the youngest component in the amp! Speakers might help if they were original, but with a head/cab there's no way to know.
Pull the chassis, flip it over and post pics of the guts. Also, the part number of the PT and OT (the number above the 606-XYY). That'll tell the tale.