I was in the same quagmire. When you begin sanding go thru the various layers. You might try in such as odd place as the bottom of the dash. This place may have the most history as it not really seen unless your laying on your back, such as installing gauges. Maybe the doors could have been changed at some time. I've got some interior shots of my interior color in the gallery, check em out.
Good luck, and HAPPY NEW YEAR !!!
Bill
