Recommended fluid for the t-case is atf+4, although any atf should be fine, +4 is just what chrysler uses in everything.
As for the manual transmission, most use syncromesh with good results. Some use 10w30 motor oil, mt1, or 75w90 gear oil. If you use gear oil, which I believe is what the owners manual calls for, make sure you get oil that is NOT for limited slip differentials, it has additives that will wear out the brass syncro blocking rings. Not sure on the quantities for the 6 cyl., but my 4 cyl. takes 3.5 quarts.