MIMF

I found a Bassman Head at a garage sale and I'm tying to figure out the exact year it is.

It has a Tube-Tag with an inkstamp of "OD" and a picture of the "AA165" circuit. The chassis serial number is A08795.
So far, I've determined it's really an AB165-circuit, based on the component-layout.
All the Potentiometer's date-codes are from 1965 (ex. 2-35-304-6508)
Power Transformer Date-Code: 606-502 (Schumacher - 1965 - 2nd week?)
Choke: 606-4-45 (Schumacher - 1964 - 45th week?)
Output Transformer: 606-747 (Shumacher - 1967 - 47th week?)
There are inkstamps inside the chassis with a 1965 and some 2-3 digit codes that I'm assuming are the assembly-workers identifying #'s
On the front, below the Jewel-lamp, there's a "Design & Circuits Patented 66". On the back, bottom-right corner, there a tiny "67". Do those mean years?

So here's my issue: If I've decoded the codes right, then there are parts made between late-1964 through late-1967? I know that Fender was notorious for building up batches of serialized components and then pulling parts at random durring assembly, but that seems like a large range in years?

Is there any other reference-point I can date it with certanty?

It's possible that the output transformer was replaced a few years after the amp was made. That would put all the other components in agreement, pretty much.
How come I can never find these garage sales?

The best-part is I got it for $5!!!! The guy selling didn't play guitar and had no idea if it worked.

All original parts, except for a 3-prong cord got installed at some point, but the death-cap was still hooked up some reason. I disconnected that from the switch before trying it out.

It actually fully works! There's a lot of crackles and pops in the backround , but I should be able to sort them out after doing a cap-job, replacing a few resistors, and a fresh set of tubes. It sounds great as is.

From looking at the Tone Lizards site, I'm tempted to try a few of his suggestions, but I'm getting ahead of myself.


EDIT: Just popped the cover off the filter-caps and it looks like someone did already upgrade them!

Crackling seems to be agrivated when tapping on a few resistors in the preamp-stage.

What a score!