Tiny, is "Dielectric" gel being referred-to above?
It looks like the references to a "gel" are referring to a
transparent colored gel (acetate) sheet/pane for an indicator lamp?
This topic recently came up on oldGMCtrucks.com
It was suggested that the gels (red and green) be "frosted" by gently buffing them with 500 wet/dry abrasive/paper.
If I am wrong about the type of "gel" being discussed above, I apologize for posting this.
