Another quick question. My fuel gauge works sometimes and other times not.
Say I could have a 1/2 tank of gas and the gauge reads correctly and the next
moment the needle drops to empty and then a few moments later jumps back up
again

 

More than likely you are going to need to replace you're fuel sending unit in the tank. It's about a 2 hour job. Unplug all your tail light connectors, disconnect you're filler neck from the bed, remove the 6 or 8 bolts that hold you're bed to your frame and slide the bed back onto the tires and bumper, and the top of it will be staring you in the face. Just swap it out with the new one and you'll be set.

 

or just replace the gauge its self that might be it

 

The sending unit in the tank is faulty and is so on most of the newer silverados. From what i remember the sending unit costs almost $400.
I set my trip odometer and when i reach 350 miles its time to re fill to be safe.
Plus if you take the bed off you might as well change out the fuel pump/strainer and fuel filter.