front propeller shaft sloppy

Well just changed my drive belt and while I was test driving it I saw the front drive shaft spinning like it was bent. So I took It off and noticed It was pretty rusty at the slip joint so i cleaned up the splines. All the UV joints are nice and tight as wel. I put it back together after putting a new rear yoke assm. on it because it seemed loose, and if you grab the shaft you can move it alot. It just dont seem right should it move at all