1500 miles and here is the history- 4 wheel balance, 2 were out of balance and one of them wasn't indexed properly. Hardness test on the tires (sorry don't know what it is called) revealed two bad tires. This took a week! Got it back, and it is much better, bu the original problem is still there. At about 1550-1600 RPMS- 55-65 mph, the thing gets rough. It only happens on the gas in overdrive. It is not loud, just a low rumble like worn tires or something. I've read the vibration posts and it seems that nobody has the real answer. Has anybody figured this out? I really want to enjoy this truck, but right now I want my old truck back.

 

5.4 3.73 LS

 

I am having the same issue on my Lariat 4x4 and it is hard to tell if it is coming from the engine, or somewhere else in the drivetrain. It is only for a brief moment until I get over or below the RPMS you stated that it goes away. Same thing, only in OD.

 

Lucky/Eat...If your 55-65 vibe goes away when you put the tranny in neutral or disengage OD (i.e. change engine rpm at the vibe speed), y'all should check TSB 04-3-33 which addresses tranny,http://66.179.14.118/forums/showthre...ight=vibration driveline, & rearend issues.

 

Grim,

Thank you for the info. How would one go about looking at a TSB?

 

Lucky...click on my edit in the above post.