normal wear items that will start failing, include undercarriage items such as wheel bearings, cv axles, u- joints, brakes, rotors, ball joints and shocks.
Engine components such as both drive belts, alternator, belt tensioners, water pump, thermostat, both top and bottom hoses, and the hoses that plug into your hvac system.
So there are a lot of items Ive listed that will no doubt fail, some faster and more likely then others. So if I were you and you have a few grand lying around, I would start purchasing items and put them on your shop shelves. Start with things that will be needed to get your truck running with little effort, such as the Hvac hoses and allows you to do multiple things at once with the same procedure. When doing the Hvac hoses, install a new water pump, thermostat, top and bottom hoses. At this time inspect your fan clutch as this is another wear item. If it spins freely as if there isnt any resistance go ahead and replace it.
I noticed you did a coolant change already, and front dif, rear dif, but didnt see you list your tranny. This is something that should be serviced as well. A new filter, is a must, and you could go with just changing the pan fluid, or you can do the complete system swap, that does not require a factory flush. There is a great informative write up about how to do that, and its highly recommended.
If you want a great ride and a little more out of your trucks performance, I recommend getting the bilstein 5100 shocks, they are every bit worth the extra coin. Inspect your wheels for play or clicking, changing the wheel bearings and cv joints is really easy and will prevent headaches down the road, do both sides at a time, and be sure to replace your brakes and rotors when doing this project. Also inspect your ball joints at this time. Those are more labor intensive, and If they are in good shape I would wait till they start to fail before attempting this one.
Have the u-joints on hand for your front shaft and rear shaft, and when you do a oil change with the truck in neutral check for play again wait till they start showing signs of wear before changing them.
It really comes down to how much time, money and how big your shop is.