I made it to 85,000 miles with the stock LLY motor, built trans since 15,000 (trans has never been out of the truck since then, still the same one at 101,000 now), aftermarket turbo since 20,000. Beat the crap out of it, over 100 1/4 mile passes, 106+ mph trap speeds weighing 7500lbs, finally gave up and cracked 5 pistons. I did not break the stock rods.
Built the motor myself with aftermarket rods at 85,000, ran it at roughly the same power level as with the stock motor, except I added twins. That motor lasted 15,000 miles and gave up at 100,042 miles. Broke 2 aftermarket rods and bent the remaining 6.
now I have 101,xxx miles, back to stock (LBZ short block), and running a completely stock tune, except with bigger injectors and twin turbos.
ben