I am no GMC expert (nor an expert of much of anything for that matter), but in my opinion, that is not original paint.
1) The parting line between interior color and exterior color is all wrong.
2) The brake and clutch pedal shafts are painted the same color gray, but they should not be painted interior color.
3) These trucks did not come with a heater from the factory, so they were never the same color as the interior. Even a truck which came with the champagne color and had a heater installed by the dealer, the heater was not the same color as the interior and they were not gray.
Your mileage may vary.
Carl
