^this. Do you see the gauge bouncing from normal temp (or even colder than normal) then getting real hot and settling back down again? Or does it just straight up run hot?
While idling or while driving? If it's only while idling, your fan clutch might not be working properly. If it's while driving hard and it stays at a steady 212 that's not the end of the world- at 212* straight water boils but antifreeze specifically does not at those temps (not only does it stop freezing, it stops boiling, even 225-230 is normal sometimes, it shouldn't boil till over at least 240-250+, especially when under pressure with a rock solid cooling system that helps keep it liquid too). A little warmer than I'd like, but not "overheating" realistically. If cruising around easy it's normally this hot, once again it's probably not damaging anything but I wouldn't want it that temp all the time either especially since it's not like it's the middle of summer or something. I like to keep my 'Burb around 180-190*, but my 2008 GMC 2500 generally runs a little over 200* and I'm not worried, pretty normal for newer stuff.
How is the radiator? Did you replace it or have a shop clean it out really good, or did you just take a 39 year old truck that had a bunch of miles on it and slap a hot engine in it with the stock radiator that's had almost 40 years worth of hard water from a garden hose calcifying in it and wonder why it's not cooling properly?
