Do you know if any of the U65 coded cars on the above list came with body colored wheels (other than black), just to rule out that any of the trunk lid markings refer to wheel color?
I only have the broadcast sheet data on the 256700 car, the other was a window sticker. See below. The wheel color is designated as T5 on line 4 and a W25 (stamped steel wheel) option code is shown on line 10. I think we can confidently say the 4 markings (X, W, R, and B) are indicative of the tire sidewall and not the color of the rim.
D