Leaking what from where? Is it transmission oil or engine oil. You can tell if its transmission oil because after a few thousand miles it starts to stink. It smells nothing like engine oil. Also, transmission oil is a much higher viscosity.
If it is engine oil then your rear seal is bad and it will need to be replaced, which is a fairly big job.
If it is transmission oil, and it is coming out near the engine then you have a bad seal somewhere because that area is supposed to be dry. It might not need a full rebuild but if you are going to take it out and pay someone else to do it you might as well get it all done.