I have a 1992 525i Automatic. What trasmission do I have?

The reason I ask is because my car is in the shop right now and I might have to have a rebuild. OR, could I just order one rebuilt from some place? I noticed lots of mention of Kirt at Autosports Unlimited. He just does ZF trannys.

So, if I have the GM tranny, could a ZF be put in?

Sorry, I'm really clueless about this. I was hoping not to avoid major trouble for a least a year. But, it's only been a month. Crud.