GM's Vortec V8 platform is absolutely brilliant. I've had extensive experience with non-cylinder shutdown Vortec V8s, to include a '02 Silverado 5.3 with 196K miles, a 2004 Yukon XL 5.3 with 267K, my daughter's 2006 Envoy Denali 5.3L 140-ishK, 2003 Cadillac Esacalade 72K. All have 3.73:1 gears except the Envoy, which is 3.42:1. These engines are of absolutely outstanding quality and really only need spark plug changes at approximately 100K mile intervals (platinum). I change the serpentine belts and belt tensioner pulleys at maybe 100K mile intervals, and easy 30 minute driveway job, as inexpensive insurance to avoid possible pulley bearing or belt failure.
The '02 Silverado's 5.3 has needed nothing except spark plugs at 100K, and an alternator at 167K. You can't complain about a 167K mile alternator.
The Envoy Denali's 5.3 and the Cadillac's 6.0 have needed nothing, except the Envoy got a throttle body cleaning after throwing a code.
My experience with the 2004 Yukon XL 5.3 is the most extensive, and best. I run about 6-9K mile oil change interval. At 267K mostly highway speed miles, it doesn't smoke, leak, or clatter, and idles and drives like new. I'm sure to always warm it up at idle before hitting highway speeds. Aside from my 100K belts/pulleys/spark plug interval, at about 255K I changed the alternator as a preventative, and cleaned the throttle body with Berryman's B12 Chemtool. At about 200K miles I replaced the knock sensors, and at about 260K it needed a fan clutch replacement. I think around 250K I changed the original thermostat that decided to be partially stuck open, and when I did that replaced the hoses as well. Even from the beginning, it would tend to lose about a 1/2 quart of 5w30 full synthetic (various brands, Quaker State, Supertech, whatever) every 1K miles, which didn't appear to be oil burning or leaking at all, I just chalked it up to evaporation. I didn't mind much, because at that rate it would get three quarts or so of new oil between every oil change. At about 230K miles I switched to Shell Rotella T6 5w40, and I've noticed the oil loss has been somewhat reduced. It runs like new, and at this point, I have no reason not to expect another 267K miles from it.
Non-engine, I rebuilt the rear axle at about 220K miles, and replaced the transfer case around 180K or so. The brakes, particularly the rear, are very robust as it has the Hydroboost 7700 GVW heavy duty brakes, and they last a very, very long time. It also has the original 4L60E that shifts perfectly.
Again, GM's Vortec V8 platform is absolutely brilliant.