I don't know if you want to make use of this table, but it may be something we could set up with Serial # ranges. I have it in Word docx.
Early/Late refers to ‘type’ or revision to the model. The S2 late version had a slot added to the shutter speed dial to accommodate the clip on meter. The SV ‘late type’ had the mirror box modified to accept the Super Tak 50mm f1.4 lens to prevent the mirror from hitting the element, and the door latch was also changed. The SV revisions also apply to the S1a.
The AP, S and K were marketed by Sears and Roebuck on under their Tower brand. The AP and S were called the Tower 26 and the K was called the Tower 29. Following the release of the S3, marketing in the U.S. was handled by the Heiland Division of the Honeywell Corporation which resulted in different branding model numbers in the U.S.A.
S2 = H2 and they may have Heiland and or Honeywell on the prism housing rather than Asahi. There are also H2 with Asahi on the Prism and H2 by the Serial #.
S1 = H1
S3 = H3
SV = H3v
S1a = H1a