I don't normally comment when a tuner comes up for sale but I just can't resist this time. Especially as Lothar has commented now ;-)
I have for some years been quietly logging the serial No's of all the FM1/SFM2's that I see for sale. I know that, to date, there are at least 40 surviving tuners. Three of these tuners don't have a serial number so I suppose theoretically they could all be the same one changing hands a few times - but I think that's very unlikely as I also know who owns them.
I agree with Lothar's other comments, the condition is "average" and it's definitely not the second tuner made.
Lothar, we need to compare our records - we might find there are even more than 40 survivors!
Regarding the AP3 that is also for sale, I still think this could be a MkII. Nick, the photo of your AP3 MkII is interesting because I wasn't previously aware that any MkII's were actually identified as such on their case. Nevertheless, there are many examples of MkII's in cases without this identification - including the two I own. For any potential purchaser I think it's really a case of caveat emptor (buyer beware). I note that it is being sold with its original test certificate. If it really is a MkII this should certify an output of around 140 Watts per channel (RMS). If it's the earlier version then the output per channel will not be much more than 100 Watts.