Do you have a problem with your current driveline?
I ran single u-joints at both ends and never had any vibrations before i installed dual cases.
When i installed duals, i made my own rear driveline with a cv that is clearanced at the tcase end. With this setup i also have no vibrations.
Keep in mind, not everybody will use one and the results vary. I have a short wheelbase and my boss told me i was going to want one after i installed my cases, so thats what we did.
