98 xj lift questions?

I have a 98 jeep xj sport I am going to be putting in the rubicon express super flex 3.5 with leaf packs. My question is what is the cheapest way to prevent driveline vibes. I heard if i do a tranfer case drop that will help or toi shim the rear axle. If so what degree shim will I need. Please help! Thanks

Shimming the rear axle will not do it. A transfer case drop might do it, but it also might screw up your shift linkage. An SYE (Slip Yoke Eliminator) is the right way to do it, and the RE "hack-n-tap" is the cheapest way to do that.