I'll second the "replace the whole axle" sentiment.
Get under there and see which it is, the boot will be torn and grease will have been flung everywhere. When My driver's side went out it would only tick making left hand turns.
Find a reputable supplier, I recommend going with Raxles. I used them to replace my CV axle, and while they were a bit pricey, when you call (they don't do online orders), ask em if you need any special bits to remove the old axle, they gave me the torx-bit I needed to remove the axle from the wheel hub at no charge. And, they were kind enough to throw in a pair of latex gloves too, because it's a messy job. There is a core charge however, but they ship you a return label to mail back your old one.
It look me like 2 hours to do mine but I work pretty slow because I don't want to screw it up since I rely on this car for daily use as well.