I have encountered this same problem before and it turned out to be the pin for the low/reverse lever leaking at the back of the case and running down around the pan edge making it look like the pan was leaking. Look at the rear of your trans below where the tailshaft and rear case come together. You will see a hole with a 1/2 in. Diameter pin in it. This is the low/reverse lever pin. It seals to the case with 1 little o-ring. The only problem is that the tailshaft has to be removed to replace the o-ring. You will also have to drop the pan to push it out of the hole. A quick way to cure this problem is to go to your local Mopar dealer and get some of thier ATF-RTV sealer. This stuff really works. The best sealer I have ever used period. Brakeclean the pin and case, let dry, and smear a little of this sealer over the pin an case and I promise you it will not leak or come off. Also, The new Mopar reinforced rubber backed gasket is the only way to go for the pan gasket.