ok so i just picked up a 92 rs v6 i know there were problems with the rear end but the guy i bought it from didn't know exactly what. as im driving it sounds fine but when i slow down there is a loud clanking sound. get the car home and put it in the air check the oil in the rear end there is none as i am pouring more oil in i see a steady stream of oil pissing out by the u-joint connected to the rear end. would i just have to replace that u-joint or will is the differentals

 

From your description it looks like the PINION OIL SEAL is shot and not end yoke. But again it could be internal parts shot from the lack of lube to due the seal leak.