ok i looked under my car today and seen a sprayof gear lube on the underneath of the car , and its all the way around the rear u joint and rear end input seal ? what is leaking , and how do i fix it ? thanks

 

I think you already told your self what needs to be fix-ed any way it might have a bit of work to do to change out your seal you will at least have to remove your drive shaft but I do not know what type of rear end you have either??? well you will need to get a oilseal puller or use a scr-driver flat head would do fine to put a new one inn you will need a socket that reaches the outer edges of the new seal depending what type of rearend you have you might have a bolt right be-hind the u-joint (normal) there should also be some brackets that hold your u-joint in place with your rear end and drive shaft. you might have this type of set up so look if you don't have a manual.