First off, slipping does not mean the
trans is toast. It means you better get it looked at before it becomes toast. If you're beyond that point and it's a bone stock daily driver, find a rebuilt A4LD from a reputable shop and "dance with who brung you". There's really nothing wrong with them in a stock application. Poor maintenance and years of neglect are the biggest reason for their failure in a bone stock car. It's not a performance transmission, but it's currently the only automatic with overdrive available for the 2.3.