The best way to find the original color is to use some 400 grit wet or dry (that is what it is called) automotive sandpaper, and using some water, start sanding through the paint in a small area, until you can identify each of the colors that the car was painted during its lifetime of service. Once you get past the last color, and are into the final layer of primer, and then the bare metal, you will know what each color was in the order that it was painted. I would start sanding on a section of the car that is least likely to have ever been replaced, such as the rear quarter panel, or the rear door. Sometimes, you can find the original color under the rubber door gaskets, or by removing a door handle. Most painters never removed these items to do a repaint, but just taped around them.
