we got the 6.0 in a week ago and is doing good! Recap, i have a 1999 ecsb 4x4, originally with a 4.8 that had the leaky castech heads, so i swapped to a 6.0 to avoid getting any more bad heads since they were on 4.8 and 5.3's. This is just our family ride and not a hot rod. Just had a 87/89 octane tune done for the 6.0. It runs great! Just dissapointed with the fuel mileage. The best i could get with the 4.8 was 17.5 on the highway. Freinds with the same truck but with the 5.3 were getting 19 being the bigger engine didnt have to struggle as much, so i figured the 6.0 in a half ton and 4l60e would get at least 18, but it aint looking that way..Looks like its going to be worse than the 4.8...other than that its great!