Back when I had my 99 gtp I put a Dyno Tech Trans in it. It came from a 98 and from what I remember a fitting was needed to attach the lower transmission line to the trans itself.
I cannot find a picture of what I did/used as I will be getting my hands on another 98 trans but for my 2002 regal.
It would be nice to have all the parts needed in hand. Does anyone know?