We thought that about the window plug but the rear window does have the chrysler tag on it just like the others. I have owned the car since 1983, bought it in Spokane Washington, from a used car place that said that I was the second owner -- never really checked on that.
I have tried to decode the fender tag, if that is the correct one, here is a list of the numbers I couldn't find out what they mean. L31, M21, M31, V1X, C26 and C55 all of the rest were accounted for in the book that I have. This weekend I will try to get a good picture of tag.