The lead turning it silver is a possibility I guess, the only thing is the area in my one picture would have been hidden behind the seat all these years. Like Carl said the paint tends to look different in different light, the paint I got from Jim Carter is said to be the right color and from an angle in the right light does look a little on the silver side only darker. There may be something to your theory. As far as durable paint the brown interior paint I've noticed chips fairly easily. Enough to make a guy cuss when you are putting stuff back together. Good thoughts, thanks for letting me know.
Steve