NP 242 SYE/output shaft play

I have a 99 XJ with 5" of lift and the NP242 transfer case. About 2 years ago I installed the Rubicon Express hack and tap with double cardan driveshaft. It has worked well for me, but I'm now starting to get some vibration. What I'm feeling is some harshness from the vehicle when I cruise above 50 MPH. It's worse when I apply more throttle, and goes away when I release the throttle. I used to get some significant vibration at 75-80 MPH, but I corrected that with new spring packs and correctly shimming the axle, but the constant harshness is still there above 50. An interesting thing: it goes away in 4WD, which leads me to believe it's something in the driveshaft.

I climbed under the vehicle and noticed the output shaft on the transfer case has some up and down play, but very little side to side play. Since this is a 99, the transfer case output seal is in the stock tailcone. When I installed the RE SYE I didn't get inside the T/C, just cut the shaft and installed the flange. I don't recall there being any play there in the past (not something I check regularly. OK, never), so I'm assuming the output shaft bushing has worn out, and the play is causing my issue.

So I'm wondering what I should do. Should I remove the tailcone and replace the busing? Can this be done? Should I upgrade to a better SYE system?

The last questions brings up another issue. Who sells a heavy duty SYE for the 242 that does not require a core return? Since I cut and tapped the shaft I would guess it does not qualify as a core. Is this correct? Any help would be appreciated!!!!

Before you spend big money, check your u joints by pulling the shafts---------Kyle

I agree, check all the u-joints first.

Michael

I'd love to find out otherwise but I was told there isn't a HD SYE kit for the NP242. I'm about to remove my front driveshaft too see if it's related to similar high speed vibes since I have a 5.5" lift and stock front shaft (with new u-joints). Just something to consider once all's well in the rear..... btw, Tom Woods Custom driveshaft can sell you individual parts for your T-case if you should need any.