Drive Shaft Question

[Mike92STX]

I bought my truck with I think a 6 inch lift on it . I have a vibration that I think is the drive shaft. I'm going to try the hose clamp balance tomorrow and if it helps have it balanced by a shop. My question is with the lift does the drive shaft have to be longer than stock, I know it is at more of an angle. U joints are both almost new. I noticed that there is a little up and down movement at the slip joint?

 

[FritzTKatt]

You could have the slip joint nearly maxed out causing that play. Is it a 1 piece shaft? EDIT: check your pinion angle. Stock angle is 6* iirc. You may need more to compensate, but I didn't.