I went overboard and did pretty much everything and anything in the first 12 months I owned the truck. Did I have to some of this, no, but I chose to for peace of mind
All new hoses, every last one
New serpentine belt, idler pully, tensioner
Water pump and thermostat and heater control valve
All new rotors, drums, pads, shoes and brake hardware kits
all fluids except trans (which was done by original owner less than 6 months before I bought it) front and rear diffs, transfer case, coolant, power steering fluid
new tires and wheels
new shocks
new wiper blades
new battery, battery bolts, cables
pcv valve, grommets in the valve covers and connector hoses
new gas cap and radiator cap
spark plugs
headlight assemblies
All new cats, o2 sensors, exhaust going in this week provided the blizzard they're predicting doesn't hit.
How much have I spent, not sure, but it's a good chunk. The truck is also "set" for the next 4 or 5 years outside of oil changes. :::knock on wood:::