This guy thinks "P = Pan American theory" has been proved incorrect:
http://www.saxpics.com/conn/docs/numbers.htm
Other sources indicate there was a P series in 1971 only, N starting in 1972. So who knows. But the markings on this horn look much older than that.
~ Saxpics was sold a long, long time ago and has not been updated since. Pete Hales took a good shot at a good database, but it was an early shot and much on the site has been, in subsequent decades, proven inaccurate.
Contact member Stocker or Badenia here....they both have done extensive recording of Conn and Pan Am serial numbers. Badenia's research was extensive, and he even got Dr. Derkson (of Conn Loyalist) on board. Stocker's list is impressive. I can also send you a list of the Conn numbers that Stocker sent to me, and which I added to. It clearly supports that it was impossible for N to signify one year, or even a few years.
~ Nobody to date has ever SHOWN a Conn sax with a letter prefix beyond N....no image has ever been provided.
~ Also, the N serials went from 4-digit all the way up and over the 200,000's....impossible for Conn Mexico to have produced that many horns in a single year, or two, or five....when the output of saxes at Conn has been estimated to have been somewhere between 12,000-15,000/year.
~ The following Alto models all have N prefixes: 50M, 6M, 7M, 18M, 20M, 21M....how likely is it that Conn actually was producing 6 different models of Alto within the same 1, 2 or 3 year period ? 4 of them substantially different design ?
The problem is, old data, inaccurate data, when left accessible online....can still rule the day. But it's quite incorrect. Other folks have put in a lot of effort to investigate and compile info on this stuff...unfortunately, those folks don't get the number of clicks Saxpics or Dr. Rick does - and neither of those sites have any interest in revising/updating, sadly.