You'll have to check your driveline angles. The difference in the angle between the shaft and pinion and the shaft and the output of the transmission. It's no different with a two piece shaft. All angles need to add up to zero. Meaning that if the front joint has 3 degrees of angle, the rear needs to have -3 degrees to cancel the vibration from the front joint.
I actually added a CV joint from a 4x4 truck to the middle of my two piece shaft.