688 movement model id help needed

[npc]

Hi All. I'm stuck. I've been through all of the catalogs from the late 1950s through 1960s and can't locate this. It has a 688 movement and the closest thing to it I can find in the catalogs is the 1962 Sea Skip, but that's not it. I'm turning to you all in hopes someone can recognize it. Or anything about the use years of this movement. Thanks and happy weekend.

stainless 688 movement.jpg (57.14 KiB) Viewed 96 times

inless 688 movement.jpg[/attachment]