front driveline vibration

[warhorse]

I have a lifted 2000 Yukon new body style. Has thec6" CST lift with the recommended front driveshaft. I've replaced ujoints and balanced n rotated tires. When I drive it without the front driveshaft on it rides smooth. After installing it again it vibrates like a constant rumble/grown and you can feel it in the drivers seat and steering wheel. I'm not sure what it could be or if it can be a number of things due to the autotrac. Thanks for any advice/input