This is the 6-speed 62TE? Both the 4 speed (41TE) & 6 speed transaxles use ATF+4 that meets Chrysler MS-9602.
Valvoline ATF + 4 is a uniquely blended automatic transmission fluid that meets Chrysler Material Standard MS-9602.
www.valvoline.com
Walmart Supertech meets this standard, Castrol does not (it doesn't have the same 'machine oil' odor).
Many filter kits come with a rubber or cork (obsolete) pan gasket and seal. The factory and dealers use an ATF-proof RTV. Other RTV formulas may break down and leak. Read the labels. There should be no need for additives.
You probably don't have a dipstick and if there are no oil leaks, you should be able to fill it with the same amount that came out (about 5 quarts/liters).
I use an old section of speedometer cable for a dipstick and go by the temperature/fill graph (about 12mm @ ambient). Listen for the light cable 'thunk' at the bottom of the pan and go no further.