It is absolutely normal for the rear drum brakes to drag in a spot. When you spin by hand you would feel and hear a scrap scrap scrap sound.
As for looseness. How loose is loose? There will be a little play in and out or up and down but it should be more of a sound you can hear rather than feel.
As for replacing the rear...
If it was professionally installed no reason to change. ford 9" are bullet proof as compared to 8 3/4 and probably a Dana 60 as well (I'll get flack for that)
Plus parts are readily available and cheaper with more variety.
