Cletis is correct. It is a GMC thing. You can replace the colored lens for these lights and the colored mylar around the gauges with Lighting "gels", as they are called. Amazon, for example, has four colors of 12" X 12" Gels for $7. Green and red are among them. On my 56 GMC 4X4 Restomod, I used a modern 4x4 lens/gel from a 80's Chevy 4X4 indicator and cut it to fit into the high beam light which was wired to the 4X4 lever switch. If you already have an add on turnsig, you can wire those GMC dash lights to indicate anything: backup, park, key on, 4x4, low on beer, etc.
