driveshaft weights
 

Does anyone have a picture a driveshaft with a weight missing?
I've gotten this horrible vibration in the driveline. I've checked everything I can think of. U-joints are good, cv joints are good, wheel bearings are fine. I was looking down the driveshaft and noticed an unpainted square on the back end of the shaft.

I'm trying to eliminate everything before I convince myself that my rear end is shot!

thanks...