I have an 06 1/2 ton with 4wd. I'm getting a vibration between 50 and 70 mph. I've had the tires balanced and rotated, and today I dropped the driveshaft to check the u joints. The u joints are fine, but I noticed the right rear shock boot was torn almost completely off. I grabbed ahold of the shock to shake it, and there is play in the tube, which also made a metallic noise. My question is could this be the problem?

 

Sure could. Is it shaking the steering wheel? Or mostly just shaking the truck?

 

Not in the steering wheel. I really feel it in the gas pedal, and in my seat a little bit. It's not in the gear shifter either, so that's what has me convinced it's in the rear. I've just never heard of this to be caused by a bad rear shock. If I was thinking, while I had the driveshaft out, I should have put it in 4wd and drove it.

 

I think I figured it out. While under the truck earlier, I noticed a small 4"x6" piece of thin metal,(some sort of heat shield would be my guess), that was barely hanging on. I assume this was catching enough wind to vibrate fast enough that I could feel it in the truck. I barely grabbed ahold of it and it came off. I just drove the truck and the vibration is totally gone. Hours of scratching my head and troubleshooting all for this little piece of sheet metal. Unbelievable.