How can i tell if my rear differentials out?

rear ends have a pinion bearing,, where your drive shaft connects to the rear end, grab that driveshaft and try and go up and down and side to side with it.. tight? if so then all good,, loose the your pinion bearing bad,,, do this at the back of the transmission too where the driveshjaft goes in the trans,, push up and down and left and right,, does it have travel,, is there leaks at either seal,, this would tell u the bearing at theat end is going bad,, also vibration could be caused by bad ujoints,, the things that connect the driveshaft to the part the goes in the trans or to the rear diff,, same thing, push up and down left and right and also twist,, if no play your good,, where did u hear the clanking noise,,?, from the rearend or trans or? update here or message me or email me and ill try and help ya figure it out,,,Art