Sounds like you have a GTP with the tapshift transmission? Either way, if the old fluid was black, and the new fluid after the pan drop/filter change is still black then I'd be looking for a replacement trans. You might get away with doing another pan drop to change out some more of the old fluid and upon refill add a quart of Lucas to it and see what you get. Might buy you some time to find a good used trans. Up to you if you want to spend the money on the Lucas and another 5 quarts of new fluid. If you do indeed have the tapshift option then you will have to find another tapshift trans. to match it, as the other 4T65-e's are different in a lot of ways.
