fluid drip at rear - yellow fluid?

[khukwgn]

prolly been asked and I did search but just wanted to check with the knowledge base

have a light drip coming from the center rear (2003 x5 3.0) - it is a clear/yellow fluid and is oily to the touch but has little odor...I assume its brakes cuz there isnt much else back there other than the diff right?

anything else it could be? The brakes dont feel as they have been effected significantly but then again it is the rear brakes and they do little of the work.

Just hoping for some more knowledge before i bring it in for service...TIA