Heater Control Light Missing

Okay guys, I have been searching like crazy on this site and not finding exactly what I'm after.

I'm putting together a standard dash on a 1971 Demon. I've got the dash on a stand and I'm starting the wiring and I do not see a bulb available for the non A/C heater controls. Seems crazy to me that there wouldn't be some sort of backlight for them. Some posts on this site suggest there's a socket just to the right of DEF but that may only be on 73 and newer.

I'm starting to wonder if there was a bulb that maybe just clipped on to the metal frame?

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