My Z71 has a LM7 (LSx based motor) and it runs strong at 153k miles, despite piston slap when it's cold. Pretty common LSx problem.

 

with close to 90000 miles on mine everything still runs like a champ. I will say the tranny went out about 30000 miles ago but that was right after I bought it from a dealer so the warenty covered that np. can't blame that on gm when you don't know how it was treated before I got it. as long as they are close to stock and well taken care of as said above it will still be a good car.