Truck will not move

I am not sure I understand the issue. I understand that the truck won't move but does it just rev like it is in neutral? What do you mean by high gears shift good? If the truck doesn't move, how do you know the high gears are fine? Does it go into first with no grinding?

Do you just mean that you can't get it moving from a stop and if you get it rolling the vehicle will drive?

More then likely this is just a clutch issue and it needs to be replaced but normally this is due to not going into gear so I am just a little confused on what it is doing.

Here are some guides that run through all this info. Take a look at this and let us know what we are missing. Thanks

https://www.2carpros.com/articles/inner-workings-of-a-car-clutch

https://www.2carpros.com/articles/clutch-doesnt-work-sometimes-or-not-at-all

https://www.2carpros.com/articles/clutch-symptoms

https://www.2carpros.com/articles/how-to-replace-a-clutch