Is this normal ticking sound

I was just curious definitely will just leave it how it is and enjoy the truck.

 

How hard is it to change diff fluid?

 

Simple
There is a plug at the bottom of the diff to drain , and one at the top to fill.
Always ….always loosen and take out the fill plug first . Then loosen the drain plug and drain the fluid out. Once drained put the drain plug back . Then refill the diff until the fluid comes out of the fill hole . Let it drip and come to a stop . Put the fill plug back and your done . One tip , Amsoil makes squeeze pouches that are really easy to use . They make nice gear oil .

 

yeah, those techs are probably blown away at all the parts under the hood that are made with some sort of magic to make them last so long.

 

Just to add on, sometimes the fill plug may not come out or destroyed trying to loosen it. have seen posts here on that.
if that is your case STOP!