hello, my friend has a 1998 f150 reg. cab short bed. with a 5.4l. he bought a rough country suspension lift 5". he has put the lift in.
even when his truck was stock it sat pretty high compared to other stock trucks. where his torsion bars mount the bracket hangs below the frame. unlike mine where it mounts inbetween the frame rails. neither him or i have seen a truck that has the mount for the torsion bar crossmember mount where it does. also he had a problem with the parking break cable when installing the kit. it was way to tight.
MY QUESTION IS....now that his truck is all done he has a very bad vibration comming from the rear. he wasnt even able to go over 5-10mph. our other friend has the same truck but with a 4.6l, same lift kit, and his drive shaft angle is no where as drastic. you would think they would be the same...has anyone had this problem or know what the cause of the vibration. thanks

 

Are the blocks in backwards?

Make sure the short side of the taper is forward, longer side back.

 

double check all the bolts some may be loose somewhere