I have a 04 Super crew, 5.5' bed that rattles/vibrates, especially over bumpy roads. I have had the bedliner removed and replaced and the dealer cannot find anything else wrong with it. They have tightened all the bolts in and under the bed also. The first dealer told me that it is normal and to live with it, after I had it in 5 times for the problem. The dealer that I am working with now has tried several times to fix it, but no luck. The vibration shakes the entire truck, almost into a bounce and is very noisy. We have another 04 F-150 crew cab with no vibration issues, so I know that this is not normal. Anyone have any suggestions? Thanks for your help.