I recently purchased a 2006 lbz 4 by 4 crew cab long bed with 68,000 miles on it. i noticed the other day a tapping sound that will sometimes act up and sound like a taser! ive heard the tranny will pop when you shift into reverse, drive etc...but on the go i dont think i should be hearing any tapping squeaking or anything . the dealership said its fine and normal for the truck to make obnoxious noise when driving! i think they are f.o.s! they said its the turbo, all i should hear out of my turbo should be a sweet whistle in my opinion:help ive also noticed the frequency correlates to the speed of the truck and can also be manipulated with the brakes.