If you aren't sure when the coolant or hoses have been replaced, do it all at the same time:
Upper and lower radiator hoses
2 bypass hoses for the water pump
4 heater hoses (either side of heater control valve which is under the air cleaner tubing)
New 16 pound radiator cap
New thermostat
Flush out and change all of your other fluids:
Engine oil
Transmission fluid
Power steering fluid
Brake fluid
Transfer case lube
Front and Rear differential fluid
Serpentine belt and the idler pulley tensionerr.
If yours still has the original style GM battery and side terminals, pull those bolts out and see what shape they are. If corroded heavily, throw them away and replace them for less than $5.00, coat everything in dielectric grease. Unbolt and clean all the battery cable connections, clean and grease as necessary.
Just because they're cheap, put a new gas cap, ensure the system is pressurized as it should be. If the filler next is crusty on the edge, clean it with a scotchbrite pad or similar.
Heading into winter, throw new wiper blades on it.
How are your headlights.....are the lenses cloudy/chalky at all? Polish them with some rubbing compound.
Check all your running lights, back up lights, etc...make sure you can see and be seen.
Check to make sure you have the jack and tire changing tools in your truck
Lower your spare tire and check it's condition and inflate it to maximum pressure.