I recently bought and installed the Bilstein 5100's all the way around on my 2005 TRD Sport DC 4x4. The rears went perfectly fine, with no issues. I do not have the TSB leafs.
The fronts took some work, but I eventually got them done. I set them at the 0.85 setting to level out the truck. I disconnected the sway bar and steering tie rods (removed the ball with a pitman tool), in order to access the shock assembly, replaced with the new assembly, and reinstalled and torqued everything to specifications.
After the install, I noticed a low speed vibration in the drivetrain. From about 20-40, there is a slight vibration felt through the floor/gas pedal. It isn't horrible, just slightly annoying. It goes completely away if I switch into 4HI, and returns when going out of 4HI.
I got BFG 265/70-17 TA KO's installed, and an alignment (toe on drivers side was only off a little less than a degree, and that was it). Vibration still exists.
Not sure what to think at this point. It is not cyclic with the wheel turning, so leads me to believe it may be between the xfer case and front diff, but I know little about such things. It's not a constant vibration, but has a cycle to it that changes with speed. CV boots seem to look ok. I have never greased the drive shafts with 120,000 miles, perhaps that needs to be done.
I wouldn't think this minor of a lift in the front would have caused this, but here I am. Anyone have any suggestions? Everything I've searched seems to be for higher lifts, like 1.5 and higher settings on the 5100's.