possible differential problems

hey guys I'm posting a question for my niece who has an 04 Elantra that has around 64k miles on it. I drove the car and noticed a loud distinctive whinning noise coming from the engine bay area. I'm some what mechanically incline with domestics vehichles, this noise sounds like that of a rear wheel domestic car like the differential could be going bad. So my question is how can I determine whether or not it's the culprit with out disassembleing the differential and if it is how hard is it to repair on my own?

Thanks in advance.....

Rich

too be honest its more likely to be a whell bearing problem.

Thanks Flave, I believe your right on the money. I had her to find someone to help her out by jacking up the car and wiggle both tires and sure enough they both had a lil play in them.

Just wanna say thanks again for the reply!

Dewain