Need help diagnosing vibration
 

Vibration started about 5 months ago. Last repair I had done before that was new rear brake calipers.
Vibration only occurs at speeds over 55mph, most pronounced between 65-70. The dash rattles, floorboard vibrates, etc. It's felt all over.
Things I have done with no resolve:
new tires
removed front drive shaft and drove
replaced both U joints on rear drive shaft.(the said it was balanced but I don't know that they had the equipment to do it?)

If you left off the gas and coast at 750rpm's, the vibration remains so I don't think it's related to the engine. The vibration feels the same speed as the drive train. If you hold on to the 4x4 shifter, you can feel the vibration there.

I just don't know what else would be vibrating? I suppose I could remove the rear shaft and drive it to see what happens.

Any advice?

thanks,

Wonder if the rear yolk didn't come loose. :humm:

Manual/ automatic/ how many miles

Auto with 91,000.

driveshaft could be positioned wrong, i've actually had this problem on my fathers dodge, take the driveshaft out but mark it on the transmission side. put the driveshaft back in 1 or 2 notches from either side of that mark. i played with that until the vibration went away. :pca1:

vibration
 

check front wheel u-joints. they turn all the time. my 04 had the same type vibration

If you say you can feel it in the t-case shifter really well I would check the t-case out. Might have a chain that is loose or something like that.

May want to check all your motor and transmission mounts as well

a friend of mine's f-150 had the exact same problem. it started around 55 and got worse the faster you went. so it was obviously rpm dependant. the 4x4 was actually trying to engage and was about $900 to fix the grinded teeth.

Thanks for all the suggestions. I haven't had much time to check each one but I'll get there. It is a frustrating deal.