Tailgate Letter Color

[Nanook]

I have a question for some of the more knowledgeable people here on the forum.
In the process of doing some repairs on my 64 K10 (Canadian Built), I noticed that the tailgate lettering appears to be the same fawn color as the interior. I purchased the truck from the original owner, (a cattle rancher) who assured me that the truck has the original paint and had never been repaired/repainted. Is it possible it came from the factory like this? I thought they would always be white except perhaps on a white truck. I would appreciate some feedback. (By the way, what appears to be overspray on the letters is actually the lettering being worn....)