I do not have a Mopar Tan interior, but I have a GM tan interior car. ('79 Trans Am)
There is quite the mis-match in the tan pieces on the Trans Am as well - and not because of aging or sun fading. I think that the different materials play a large part in how the color appears. Whether it is a plastic piece, vinyl, cloth, or leather. Some cars have a mix of all of those materials - and thus they all look a little bit different!