i have an 2005 f150 4x4 6 inch lift with 2 inch aal and 2.5 levelint. just the other day i was leaving my house and loud viberation inside the truck acured. i went and had it looked at and they found a bad front wheel bearing so i changed it and still the noise is there i had all my tires checked and alignment the noise is coming from the rear in the driveline i think but no one around here knows wat it is inless they start pullingt it apart and before tht i would like to see wat yall think. the noise and viberation accurs at speeds above 40 mph only. i also pulled the rear diff cover off to check the gears and change oil and its all good. idk wat it could be...if u have an idea let me know
thx

 

Two piece or one piece driveshaft? With 6 inches plus I'd suspect the U-joints.

Just my $0.02

 

its one piece i believe. i have this lift setup on for about a month. u think i should check the ujoints and they extend the driveshaft with the spacer?

 

Anyone

 

Yes check the u-joints, it's not just the length of the drive shaft but also the angle. When you lift the truck it increases the angle of the shaft which puts stress on the u-joint. If yours were border line before the lift then it may have finished them off.