Had a busy Sunday changing parts to be preventive. The truck just turned over 150,000 miles and was still on its original radiator, fan and viscous clutch, and alternator. In addition, the turn-signal relay failed so that the signals would work erratically, then stop (the emergency flashers worked normally). All of the above were swapped, but I saved the old parts just in case, since they still functioned.
The alternator was a new Motorcraft. The relay was aftermarket. The fan was Motorcraft, but the viscous clutch was aftermarket, and I bought the special tools for that job cheap from RockAuto. The radiator was an aftermarket all-aluminum replacement, no plastic on the sides. The coolant was all Motorcraft Gold.
The radiator was plug-and-play except that I had to trim the fan shroud top and bottom to be able to attach the shroud properly. I also put Teflon tape around the ATF line threads as a precaution. After bleeding the system of air, which took about half an hour of running, I had no evident leaks (good thing, as I made a mess with spilling some coolant anyway). Running around town put the temperature gauge at exactly where it normally had been, just below halfway between C and H.
There is some fan noise at low engine speeds until the engine is warmed up. The new viscous clutch is a little stiffer than the old one, and trimming the shroud probably contributed to the fan noise.
I got about 3 gallons of coolant out and put about the same in, including siphoning out the overflow tank and refilling it, so I got most of the old stuff out.
If I had to, I could put everything back as it had been except for buying a replacement fan shroud.
Fun fact: today I stopped at the dealer to get concentrated Motorcraft Gold to replace the stash I used for the job. The concentrated stuff is nearly $30 per US gallon now. Premixed Motorcraft 50/50 is just under $20 per US gallon. The generic aftermarket gold coolant at the auto parts stores seems to be available only premixed, not as concentrated.