I recently put a 3.5" RE superflex kit on my 05 TJ.  I did install the transfer case drop kit and I'm getting a vibration.  The vibration occurs when I get around 50mph and it sounds like this "vroom vroom vroom vroom" I think it may be from the driveshaft but I'm not sure.  When I let off of the gas it goes away but returns as soon as I give it gas again.  If it is the d-shaft I was wondering if cam bolts in the lower control arms will solve this problem.  I really can't afford a SYE and a CV driveshaft at this time unless I want a divorce and I figure it's cheaper to keep her.  Please help this vibration is driving me crazy.    

Get an angle finder and check the yoke angles on the rear t-case output and the rear pinion. You may only be able to eyeball it. They should be parallel. If they are not, your driveshaft will vibrate.

Once you add a CV driveshaft and slip-yoke kit you can point the pinion up, inline with the driveshaft.

I highly recommend the tail shaft kit and CV driveshaft. I consider it mandatory with a lift kit on a TJ.

My 97 TJ has a driveline vibration.  I have a 4" FabTeck kit and SYE with a cv style drive line on it.  I am still getting launch shudder and a shake around 35mph and above.  Any advice would be appreciated.