driveshaft moves 1/4" up and down at support bearing. Acceptable?

I am troubleshooting a highway-speed vibration that appears drivetrain-related. The tires/wheels are known good and balanced (as is a second set of tires/wheels). The u-joints are tight. But, I can move the rear driveshaft up-and-down about 1/4" at the center support bearing.

Is this within the acceptable tolerance, or is my bearing shot? Anyone been there, done that?

Thanks,
Dave

 

normal

 

ok, thanks