Drive shaft vibes?

Have several questions regarding drive line vibes.

Between an OEM and lifted vehicle which would place the yoke out further?

With a 3.5" lift are shims recommended?

What about a SYE and Driveshaft?

Noticed that when one takes their foot off the gas and is coasting it sounds as if there are some rather large rocks being ground down in the transfer case area. Curious how much damage I'm doing by simply driving the vehicle.

Regarding the driveshaft it is sitting at 18 degrees with the yoke approximately out 8" from the back of the transfer case to the center of the u-bolt

Any help / advice would be greatly appreciated.

SYE and new driveshaft? Yes, definitely. The grinding sound you hear is the slip yoke bouncing around on the transfer case output shaft due to insufficient spline engagement (thanks to the lift).

Shims? Maybe. Depends on the resulting driveline angle following the SYE installation.

I just installed a Tom Woods SD SYE and driveshaft combo on my XJ and it cleared up the same grinding sound issue and 98% of the vibrations. I still get a bit between 30 and 40 MPH, as well as over 70 MPH, but nothing like before. I will ultimately need slight shimming (just haven't measured the angles yet). I have a 3.5" RE lift, which sits considerably higher than 3.5".

Follow up question then would be are all Slip Yoke Eliminator Kits created equally? Which would be the most reliable?

Advanced Adapters and Tom Woods seem to be the top picks. The Tom Woods Super Duty SYE is basically the same thing as the Advanced Adapters one, but has a better warranty (lifetime replacement + $100 reimbursement if it breaks) and opts for an output flange instead of a yoke. The flange allows you more flexibility if your build plans change (such as going to a beefier axle with larger U-joints). I opted for it with a CV driveshaft since it was only $50 more than their AA combo - well worth the warranty IMO.

Most HD SYE kits are pretty equal in the eyes of what most XJs endure (we're talking HD kits here - not hack-n-tap). Pretty much all of the common options are in the same price range ($200 to $300)... This includes Advanced Adapters, JB Conversions, and Tom Woods' Super Duty SYE.