Well, it could be leaking from a few different areas. If it's the passenger side it is most likely the kickdown cable. It is a huge leak point right where the kickdown bolts to the trans. The little washer just can't hold up after years. An easy fix for me was to go to the local plumbing store and buy a square stock of flat rubber, cut out my own rubber gasket. Never leaked again.
Other possible problems could be leaky lines, bad seals, or even a bad pan gasket. Fill 'er up and see where it's leaking from, then go from there.