For a while I also had automated searches running on e Bay for these 14 amp types - whenever one appeared for sale I would contact the seller, asking for the serial number.
9 out of 10 did - many thanks to them for their trouble and good will.
latest updates; small changes to a few amp batches dates, Dec 2015, Feb 2016, July 2016, Sep 2016, March 2017, Feb 2018 small changes to 4 amp batches, Nov 2015 typos found, two edits, thanks Ben H, June 20 info updated, totals unchanged Oct 2014 really nifty table design Aug 2014 small data and totals updates Jan 2014 (info updatedthe website I developed for this amp's care and feeding, .
Eventually, I thought, I'll get a rough idea what the highest and lowest s/ns were.
Please note that fender serial numbers tend to overlap by at least a year, and thereby the date of your guitar can only be approximated.Compared to my estimate of the total made, that's more than one in forty.It might not sound like much, but quite a lot can be deduced from such a sample.I would have to collect data for ALL the amp types, just to work out how many were made of mine.Then I became aware of the amazing work Greg Gagliano had been doing since the 1990s - the summary of his latest results are here - and that his research didn't take in the Rivera-era, or anything later. However for this range of amps at least, I reckon it's not just a policy of withholding company-confidential information. It's no criticism of Fender to suggest that they were too busy making great amps to keep records just so some amateur could use them thirty years later.