Good guess but this time no not specifically .Trying to understand if maybe a early or late issue in production , different plant issue ,or random at any given plant.
Ok can't address the guestion for NJ cars . Not enough samples and very difficult to get any pictures considering where they are installed on the car at any plant.
Have not looked at Dearborn cars yet but for San Jose it appears that the vast majority of them were bare steel though the other provider supplied some during the production year. Either they had extra from supplying one of the other plants so they sent them west but a small number of black painted ones turned up in the search. Based on where, during production, the bare unpainted ones were found it appears that the supply had nothing to do with month of production as they are found on cars built from the very early period to the very late production periods. T
With more information we might be able to determine when the black painted ones were shipped, received and used at at least San Jose like we've been able to do with a few other items All are from two speed wiper assembles except possibly the early center picture. Don't have a window sticker or other documentation for that car
Here are just 5 original examples center - 6R12xxxx, Top left - 6R130xxx , Top right - 6R176xxx , Bottom left - 6R191xxx , Bottom right - 6R187xxx (the black painted one)
Hope this helps
