OEM thermostat is 190 deg and many/most/I run a 180 deg. The worry is that an bad/extended overheat will deform the block. Blown head gaskets are not uncommon on these engines. I get nutty if I'm over 207 but that is probably more about my paranoia. That said, if 210 is 'normal' for you, it won't take much for the truck to overheat.

There are dozens of over-heat threads. Generally the progression is, new t-stat and flush & new cap for the reservoir ---> fan clutch ---> radiator re-core (or replace).

 

I have always liked the way my fan clutch was tight (noisy) at cold start up for 60-90 seconds and then got quiet.. assuming till it warmed to the appropriate temp. Sad to say that with the secondary fans running I never tested the clutch at those temps. My number 2 has a bad fan that is noisy from the start.
Got a good one at a bone yard today.. I will be swapping them out to see if that keeps my main ride cooler this summer.
I think the ground issue is causing an erratic temp gauge though.