275k on my 2003 tahoe, 5.3.
Runs like new.
I put a new (well, used, from the junkyard) trans in it at 230k. (original 4L60 lost 3rd/4th gear) Only other "big" problems were a front right wheel bearing, ABS module, and transfer case encoder motor. The front end (tie rods, pitman, idler) is...