Hi I was changing the engine oil in my 07 Equinox AWD and when I was checking the rest of the vehicle over, I noticed the output shaft seal must be leaking on the rear left side. There is oil running down where the shaft goes into the the rear transfer case. Is this a hard job or should I try it? Do I need special tools? How is the shaft held in? I have changed the many seals on vehicles before, but never on an AWD.