I have checked Accessory Price Lists from November 1950 through April 1955. The part numbers on the P&A Broadside are the only ones listed for outside rear view mirrors on a K-F product. It should be noted that the April 1955 Willys Motors accessory price list does state that the numbers are good for Kaisers only.
Our HJ has non-factory mirrors put on the car by a prior owner. I don't know if the actual mounting template was used, but while they do their job, they were mounted on the car at a position that prevents opening of the door vent windows for better air circulation in the summer. When (or rather if) we have the car re-painted at a future date, we will replace them with correct items.
Mirrors for better visibility are (within reason) considered a safety item or at least has been in the past.