Like many of us, a couple of the nylon nuts that snap into the rad support had broken tabs. I first tried Dorman 42119, but the black part is too small, the top mount allowed the light to flop down and point at the road.
I tried 3D printing a file, but it was a bit too wide. I opened Fusion, and was starting to revise the file, but I found a different option. Dorman 42117. One in stock at my local place, decided to try it out. Different design than the stock 60-66 style, these look like license plate mounts. Happy to report that these bushings snapped in place like they were designed for our trucks. Searching on our forum, I found only one other reference to this, over in the 67-72 section.
Top image, 42119, don't buy these. Bottom is the winner, 42117.