Well, the plan was to take the sidekick down to the States with Muskeg Tracker on a long trip but there were a few bugs that I could not work out. After my highway drive, I realized that there was a drive line vibration that appeared when I floated the throttle and decelerated. The rear differential got smoking hot too. Not knowing what it was, I started with the simplest thing and tried dialing in the pinion angle more precisely. No matter what combination of lengths I tired, I could not get rid of the vibration. I tried a spare driveshaft. I shortened the lower links to 19 1/8" to get the slip yolk into the t-case further.
To test for vibration, I put the axle stands and put it in drive. (making sure I had a straight shot if it by some freak chance it slipped of of the stands and jack). At about 60 km/hr the vibration would appear and not go away. I then removed the lift springs. Installed the stock springs and re-adjusted the pinion angle for the lower height. Stuck it in drive and no vibration.
As a last ditch effort, I called Geoff and he told me to lengthen my upper link. Tip the pinion back so it almost points at the t-case. He said I know this is against the recommendation for u-joints but they have had luck with it. He also said that they have had problems with using 235's and 5.13's and the 3 speed automatic. The harmonics of everything causes resonance within the driveline.
I was out of time and therefore had no more time to adjust the pinion angle again after messing with it for 2 days.
Talon, you may have problems with your lower links being so long. The slip yolk may be too far out. If the pinion gets tipped back, then that would lengthen out your upper link anyways. Hopefully you don't have the woes I've had. Approx 1/10 lifts Geoff has done have had these rogue vibrations and it has been everything from pinion angles to wheel balancing.
Sorry for not posting pics yet.