First thing has it got a trans dipstick tube?. If it has not i send mine to local automatic trans specialiast.If it has,after 5 mile run drain and remove pan ,slacken valve body (do not remove )drain as long as poss. if converter has drain plug (some dont) drain .Replace with exactly same amount of merc supplied oil.Check level at 85degrees after 5 mile run with special dipstick ,renew red security clip on dipstick tube cap.
Steve Sneap.