Engraved serial numbers on pre ceramic submariners and explorers

[rollee1]

For pre ceramic sports models like 16570 Explorer II and 16610 Submariner. M serial and after.
I'm wondering if there is also engraved serial numbers in between the 6 o'clock lugs, in addition to the one found on the engraved rehaut.

For the current ceramic models, the serial number is only found on the rehaut.

[Alpino]

.

Serial can be found between lugs for current models ceramic or not. It dépends on the year of production.

This s/n between lugs was abandonned with the random s/n and some G serial.

It's the same rule that apply to last 16570 and 16610 with engraved rehaut.

[fskywalker]

My M serial datejust 116269 TOG have both, my sold M serial 116200 also had both. I think most M serials across the line are like that