would it be easier to (a) just buy a complete front axle or (b) replace the ring and pinion gears along with the seal where the driveshaft is? ive never done either. my buddy borrowed my jeep, and called me because the front end was grinding. i pulled the diff cover and there was hardly any fluid, alond with chunks of broken teeth. any advice/suggestions? any write ups or how tos?

Cheaper and easier to swap the whole axle with a doner from the boneyard, just make sure the gear ratio is the same.

Agreed, unless you are using this opportunity to install new ratio gears or a locker and axles, or...? Setting up new gears is NOT for the average shade tree mechanic and takes special tools and skills to get done correctly, but if you're running taller tires (or plan to) this may be the time to have a shop install new gears and rebuild your assembly with new bearings and seals. Can also install some better axles too.

But, the cheapest, easiest and most straight forward thing to do is swap in a used axle (with the same gear ratio) and call it good.