Note the pencil marks on the side.
Interesting that you noted the pencil marks. I just restored my original regulator. I documented the pencil markings and re-applied them in the same location after the base was re-plated. It's good to verify that these were original markings.
68 L30/M20 Convertible, Ash Gold
N10, F41, N34, Z21, ZJ9, Z87, D55, G80, P01, U17