The transmission will shift into gear but the truck will not move?

Yep, there are some things we can check starting with the fluid level, this guide can help you:

https://www.2carpros.com/articles/how-to-check-and-add-transmission-fluid

If the fluid level is okay, when you put the truck into gear, have a helper look under the truck from the side, near the rear of the truck to see if the driveshaft is turning without the truck moving. This will be a sign the differential is having an issue not the transmission. Also, put the truck in reverse and have the helper see if the reverse lights are on, this will help us see if the gear range sensor is working. Please upload pictures or videos in your response to any problems so we can see what to help you with.

The drive shaft is not turning, you can hear it catching almost but won’t move, the reverse lights are working. What next?

Did you check the transmission fluid? And if so, please give it a smell to see if it has a burnt smell to it. If it does smell burnt a transmission service may help it, we should run the codes as well. These guides will help, and I have included the instructions for your truck in the images below.

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

and

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing



Fluid Types


Transmission Fluid Type

4R100 .................... MERCON V

4R70W .................... MERCON V

MERCON ATF is being replaced by MERCON V ATF as a service fluid, per TSB 06-14-4.
Capacities
Transmission Fluid

4R100 .................... 15.5L

4R70W .................... 13.1L

Note: Approximately Dry Fill Capacity

This video shows it as well.

https://youtu.be/HJdcWI6m3J4?si=FTjNhwkDU24UEl5q


Check out the images (below). Please let us know what happens.