Is the play there with the U joint installed on the drive shaft? If so, you need a bushing. It's normal for the shaft to move up and down if the rear half of the yoke is removed because the slip yoke is what centers itself in the bushing.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!