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