The factory color matches about anything. I bought what Jim Carter calls the factory interior paint, but found it quite a bit darker than spots on my truck that were protected from fading. I had that paint lightened a bit locally to get a closer match. I don't think Jim Carter will divulge the paint code (and I was unable to find it anywhere) for the interior paint, but if you have a part (seat riser skirt, etc) that can be taken to an auto paint store, they can match it. If not you could probably use Jim Carter's color and no one would know better. He supplies PPG ALK200 paint, which is an alkyd enamel and applies easily.
47-52 Interior Paint[on edit]TCP Global has the attached that they matched from and original part (the one on the left). But I don't know what that would look like on an actual truck.