If you didn't have any fluid come out of the knuckle assembly when you pulled out the drain plug then you should check the seal where the c.v. shaft goes through it ( the knuckle). It's a 2-piece seal on the inner side of the knuckle. If you see any oil residue on the knuckle or on the seal it's most likely from the seal. You can also jack up the front end and try to wiggle the tire to check for play. Make sure you use jackstands under the front end for safety. Grab top and bottom on the tire and try to move back and forth. This will help you check the bearings in the knuckle, if they're bad you'll feel it. You will feel the play, and may have somewhat of a klunk when you go back and forth. If you can get someone to help you wiggle the tire it will be easier to see if the knuckle has any play, you look while they try to wiggle the tire. Hope this helps you i.d. your problem, good luck.