Transfer box shaft lift

I have a vibration when under load at about 40MPH - much worse when towing (approx 1.7 tonne).

Have looked at prop and looks ok, no noticeable movement in splines or joints.

Whilst checking over, noticed that there is approx 1mm lift in the front output shaft from the transfer box.

Is this too much and could it be causing the vibration?

thanks

if its loose yes but as front bearing is a ball bearing shaft will pivot on it giving a little movement unlike diff which should have none as it has taper bearings