i have a 97 f150 5.4L 4x4 don't know what Tranny have but i do know when i ford a creek or deep puddle i noticed that i get a hole lot of fluid coming from the fording plug in the bell housing. one time it dumped almost all my fluid and when i tried to refill it dumped it back out and would not drive due to the lack of fluid i parked it over night and refilled it when it was cool and it has been fine. this has happened 2 times. i can only assume that the front main seal is hot and when water gets on it it cools and lets fluid out. my fording plug is new and keeps a good seal. when it happens and i pull the plug i get a whole lota fluid dumping out of the bell housing. i need help i cant get to my fave fishing hole like this. thanks

 

That plug is for keeping out dirt and dust not stopping a leak. If there is fluid behind it you have a converter,front seal or pump gasket leak. The transmission has to be removed to fix it.
Alan

 

this i know buy why does it leak only when i go in water???