OP, you are aware that the 6.2 is a fairly stout engine and that the 3500 red line is no doubt for some wet behind the ears GI that has a heavy right foot?
6.5L Diesel Land Speed Truck, Bonneville Salt Flats, 6.5L Diesel
this guy has campaigned a 6.2/6.5 diesel at Bonneville salt flats for THIRTY YEARS.
they have taken the 6.2 up and over 5000 rpm with no damage.
NOT suggesting YOU do that with yours, but read the article and understand that these engines were also used in a MARINE environment, where the RPM was higher than that 3500 rpm.
just something to consider
proper maintenance, judicious driving and not just beating the snot out of it will keep you driving your truck for a LONG time
I use Royal Purple in mine (engine, difs, transfer case - but not the tranny) and I've not had ANY issues. I don't hot rod either of mine, but I also DO NOT WORRY about the occasional and short burst of up to 70 mph - say to keep from being crushed by a big rig that just 'changed lanes' without regard to what was occupying the lane where he was going...