Driveline noise/vibration

[Precisionw900]

I just went through this fight with a truck. Rebuilt driveline, new slip yoke and all. New brake drums all new tires. Alignments you name it I did it. What I finally found was output bearing on transmission was loose. Surprisingly I couldn’t feel anything pulling on output shaft when drive line was down. Once driveline was reinstalled I guess with the added weight hanging I was able to push up on yoke and feel slack. Remember a drive shaft acts like a large stethoscope. I can really amplify a vibration. Is your vibration high frequency? Drivelines usually are fast vibration and anything wheel end related is a slower heavier type vibration