rattling sound from lower unit

[bigisland]

When running the montor on the hose I noticed a high pitch rattling sound.Seems like its coming from the lower unit and sounds like something might be loose.It sounds like it could be like a thin piece of metal cause of the high pitch sound.Does not have the sound on the other motor.These motors are 2003 df70.Any ideas?

[boats.net]

Check gearcase oil for metal or water in it. Remove lower unit and look for something loose.