I have a 1984 Dodge ramcharger 4wd. i just did an all around fluids change on it on sunday and when i was driving it home from work yesterday it started making a really bad grinding noise when i let off the gas. it makes this noise in all gears when its in drive and if im coasting it even does it in neutral. it stops making the noise when it gets below 10 MPH and whenever I give it gas. i got a new trans filter for it and used chrysler +3 atf. i went to check the fluid levels and it was over full, almost black and smelt burnt to all hell. (when i changed the fluid i made sure to keep it at the right levels and warmed it up and drove it to get it moving through the trany and checked it again and it was fine) it still drives just the same and shifts smooth. just when I cost it makes the noise. any help would be greatly appreciated.