I do know what has and hasn't been done. The previous owner is the original owner. It's had 1 trans and one alternator, oil changes, 2 windshields and one back window, spark plugs, wires, air filters, cabin air filters, tires, and the AC system was resealed at one point. EVERYTHING, and I mean everything, else is original. Obviously, all highway miles.
The coolant didn't freeze at -40, I can pull with the truck in 105 degree heat with the AC on and it won't overheat, so I ain't changing the coolant. Preventative maintenance can only go so far when you have 311K miles. Chances are the water pump isn't long for this world and I'll just flush the cooling system when something fails. You guys can loose sleep over it if you want, but it sure doesn't bother me none.
Also, Dexcool only tends to break down when oxygen is allowed into the system ie from a leak, or when the cooling system can't build much pressure (ie leak) and goes through a ton of heat cycles. My truck obviously didn't go through very many heat cycles. The coolant still feels great, it isn't gritty at all and still feels plenty slippery.
I bet you'd be shocked at how many old vehicles out there STILL have the original dexcool that has never been changed out. Last summer I changed out the original dexcool on a 99 Sedan Deville. It was obviously time. There had been a cooling system leak and the coolant was filled with little chunks and had lost it's lubricity. My 97 K1500's coolant looked original, it was all clumpy and the radiator was starting to plug. Shortly after the intake manifold gaskets started leaking internally. I swapped that over to green coolant, put the steel backed gaskets in and never looked back. My grandma had a 2003 3.4 grand am that she bought new, never changed coolant on it. When she sold it last year, the coolant still looked brand new. Dexcool changed around 2001-2, it only caused issues in older vehicles.
TL;DR I don't care what you think about my coolant being original. I have seen enough to know when its time to change it, and it isn't time. I was simply just stating a fact about the reliability of LS engines, which are IMO way better than an old school big block.
Hopefully the thread derailment is over now.