T300 Bell Housing

Usually any time you find stuff on the bell housing it is most likely from the clutch itself. There is nothing else in the bell housing that a piece will just fly off from so I don't know how long ago you replaced that clutch but most likely it will start giving you issues like sometimes its not going to want to go in hear and most of the time it's going to be ok till it finally just gives out all together

 

Does it grind going into gear? Why did the clutch need adjusting. What your describing sounds like its a piece of the clutch brake. If so this is why your needing to adjust the clutch. It may not need adjusted just a new brake installed. You should be able to look up in the bell housing and see if the clutch brake is there or not. You may need to use a extendable mirror to get a good view. If it looks to all be intact reach up and try to spin it with your hand. If it spins the ears are sheared off and it needs replaced. Usually takes about 45 mins for me to do one at the house

 

I have also had shops replace the clutch brakes before and Leave pieces of the old one sitting in the bellhousing or in the cross member under the tranny.

 

The clutch brake would only cause it to grind when putting it in gear from a stop. This is assuming it has a non synchronised transmission. I'm not familiar with what they put in those smaller trucks.