Vehicle speed sensor location I don't know where to find it?

Here are some guides that will help with testing and replacing speed sensors in case you need this info as well:

https://www.2carpros.com/articles/abs-wheel-speed-sensor-test

https://www.2carpros.com/articles/how-to-replace-an-abs-wheel-speed-sensor

The reason you are having an issue finding it is because Ford only used one rear sensor in the rear differential on these trucks.

I attached the process below from the manual. Please run through this material and let us know if you have other questions. Thanks