the one in the 18 silverado is original as far as i know I bought it in 19 so it's fast approaching 5 years, it will probably be my next victim I have only had the water pump fail so farI'm knocking on wood here talking about it, lol, but I've only ever replaced one radiator in the 6 vehicles that I currently own. That was in my Mustang, not because it leaked, but because of the bigger, supercharged engine I put in 15 years ago needing a bigger radiator.
My two highest mileage vehicles which were bought new, the 2001 Yukon with >250k miles and the 2002 Mustang GT with ~170k still on original radiators