[GreenKeys] Model 15 serial numbers

[Jim Haynes]

The place of manufacture is surely Chicago, but I don't have any 
information on serial numbers and dates.  I've seen figures like 100,000
and 150,000 for total production of Model 15s.

Those who have ex-military machines might find them stamped with an
inspection stamp and date, or with a MFP stamp and date (moisture and
fungus proofing) and that would establish a latest-possible date of
manufacture.

There are some products, like collectible radios, where people online
have established registries of serial numbers to try to determine date
of manufacture and total number manufactured.  Maybe someone wants to
do that for Teletypes.