Tranny "shaking" when put in drive/revderse

[jawbreaker]

Help! This weekend when I put my 92 explorer in reverse the whole vehicle shook something terrible for a brief second then everything was fine. This happened twice but sporadically the other times it acted normally. The fluid is fine and the truck shifts smoothly. Any ideas?!!

 

[wesner1960]

when my 2002 ford explorer is on park it run great but when i put it on drive or reverse the rpm drop close to 6 and it starts shaking can some one help with that essue.
Thanks