With a double cardan front drive shaft, like the JE Reel one, you will have to get the pinion angle right, otherwise it will vibrate. On mine anything over 7.5* will cause vibration. Try pulling the front drive shaft and see if the vibration goes away.
Another thing to consider, if you have after market rims that are lugcentric you need to take your time mounting them and make sure the lugs pull the tire so it is perfectly centered. I had the same problem with mine, had them balanced twice and still had vibration. Changed the lug nuts and the vibration all but went away, spent a few minutes making sure the rim was centering properly and the vibration completely went away.