I’m still trying to research the details, but I believe the Rolex 6034 utilized both the Valjoux 72A and 72B. Unfortunately, lacking any movement images of the black dial Rolex 6034 (as always, please let me know if you know of any), I can only go by what is included in transaction text for these pieces, which is either Valjoux 72, 72A or 72B (the Valjoux 72 includes a 12 hour counter). We can at least visualize the distinctive U-shaped bridge and 9 pillar column wheel and pusher at 2:00 slightly closer to the crown than the pusher at 4:00.
I have read of the key differences between the 72A and 72B [1]:
– 72A used a regulator, whereas the 72B incorporated Microstella adjustable-inertia balance wheel (a pair of screws located on on the rim enabled the frequency to be adjusted).
– 72A flat hairspring was replaced by a Breguet overcoil hairspring [I am not certain this was the case]
However, one movement seen appears to have both a regulator and Breguet overcoil, with:
– Stamped 72 with Valjoux logo
– ROW on the balance cock
– On the bridge:
MONTRES ROLEX S.A.
GENEVA SWISS
ADJ. TO 3 POSITIONS
SEVENTEEN
17 JEWELS
– On the cock:
SWISS MADE
FAB. SUISSE
[1] Rolex Daytona Movements By Pucci Papaleo, 1 November 2013