Sweet find.... answered all my questions....
Dirks response for easier access -
"B-series Luminor Base
January 13 2008, 2:23 PM
1500 is the total for all B-series Luminor Base models, includes references OP6502, OP6520 and OP6521. Asi was once able to get a look at a Panerai Marketing & Communicazione Note for ADs and the split-up was 700x PAM2, 400x PAM10 and 400x PAM 9.
For the B-series Luminor Marinas (3000 pieces), the split-up was 1500x PAM1, 699(!)x PAM 3 and 800x PAM4, covering OP6502, OP6518 and OP6519 case references.
Want to know the split-up for A-series OP6502? Here they come:
Luminor Marina: 900x PAM1, 250x PAM3 and 350x PAM4
Luminor Base: 500x PAM2, 250x PAM10 and 250x PAM9
Ignore the millesimation number if your watch is an early A or B-series watch. All sorts of funny things happened there. Here are two OP6520 B-Series Luminors. One has BB987400 and B0174/1500. Other one has BB983557 and B0260/1500. Ignore the millesimation number, as the second watch (0260) was produced 3843 watches BEFORE the first watch (0174). Would be quite interesting to know the BB-number of your watch (1281) ....
One more thing, I forgot to mention the 00R PAM 2 in my first post. That one has also case reference OP6520 (SS Luminor Base, Solid Caseback and Luminova dial). Same logic as for the OP6519 reference for the PAM 195 (PVD Luminor Marina, Solid Caseback, Luminova dial)