did you replace or reface the rotors? if the surface was ground up and rough when you put new pads on they will wear down quick. and pictures would help

 

Here is a pic of the old pads

 

 

 

Typically, uneven brake pad wear is caused by a caliper sticking.

Is your truck a two wheel drive or four wheel drive?

Did you use all new brake hardware?

 

When you say "I changed the calipers and pads" do you mean you took some off of another truck or that you bought new? Looking at your pads I would guess the latter, because it looks like you have some pistons hung up and not working (on the pad that isn't worn) or pistons not returning (on the worn out pad). either that or you slapped them on rotors that were already ground metal to metal on that side and ate the pad because of the rough surface. The pads are the symptom not the cause, pictures of the rotors and calipers would be far more helpful since it doesn't take much imagination to understand what you meant in your original post about pad wear.

 

 

 

 

 

 

Looking at your picture you can see the outside of the rotor is much thinner than the inside. That tells me it was likely ground metal to metal for a while and you probably ground off the new pads on a rough surface, also the outer surface of the rotor will now get hotter faster than the inside and that is why your pads didn't last. This is also why brake repair technicians measure the rotor thickness to see if they can reface them, or they replace them when they do a brake job.
This may have all started with a bad caliper (stuck pistons on the inside). All you really need now is new rotors and new pads (again). The only right way to do a brake job (safety is on the line here) is to put new flat pads on a flat rotor surface and you need to be sure there is enough rotor thickness left for proper cooling. if you put new pads on a grooved or ground up rotor you will not get full contact until the pad wears into the shape of the rotor surface and you will never get proper braking out of it. Problems can include: pulling to one side under braking, poor stopping power, poor pedal feel, squealing, grabbing, short pad life, brake fade etc.