Recently I bought a decent Bulova Senator with year Mark M0 on the case. The movement seems not original as it has N0 as year mark. Fortunately I have a few 11AF movements in stock (L9, M0 and M3) which leaves me with 3 options:
1) Bad luck. Leave the N0 in.
2) Replace only the N0 barrel bridge for a M0 bridge.
3) Replace the complete N0 movement for the M0 movement.
Appreciate your comments...