The issue in this case was it was a part for an apparently rare combination of equipment.
On one hand, while its nice to play Mr. Potato Head with ordering your ideal truck, it can result in situations like this where although the F150 is super common, you end up with a part used on a very small subset of them.
When it comes to the bread and butter parts, it is easy to find parts for these trucks - virtually anywhere. When it comes to a specialty part like this (which unfortunately controls a rather normal function), that's where the trouble starts.
Also, the Ford Parts numbering system makes a ton of sense once you understand it. Far from just a random jumble of numbers...