You left the & out.
LC&D.
My guess Trav meant the Large Crown and Diamond molds.
IMO there is no way to say the Skeys is an east coast mold or used by people that moved west.
Skeys and hubs are the most used molds all over the country at the time they were made. There are 15,000 hub records. My guess there would have been at least that or more during the hey day of the Skey.
AND:
The small key is till being made today. The mold is owned by a CA company.

"Tony Cornero was a California boy and all his other chips reflected typical West Coast usage."

Tony also used C&S chips from Cincinnati. Also sold all over the world.
Diamond molds were sold everywhere. They came out of Kansas City.
Lcrowns are mostly CA.

I've never seen the chip in your scan that I can remember. BUT: A ton of SS Rex showed up a few years ago. An ebayer had boxes of them. I don't remember what they all looked like.