Since these letters are manufactured, there is no reason to assume that they are based on a font. For the purposes of manufacturing the letters, changes might have been made, even if an actual typeface was the initial model.

If a company made this sign, they may have their own custom alphabet they use for this sort of sign work.

I couldn't find any serif font/typeface that matched this, looking at over 1,900 families in the Serif Guide.

My guess is custom for this.

- Mike Yanega

You're right, Mike. This typeface is called "Architectural" and is used by Gemini Plaques. I don't know if it's commercially available.