Here is the inside of my throwout bearing. Nothing is obviously wrong but as I posted above, when I shook the bearing, it rattled:

[IMG]http://i7.photobucket.com/albums/y261/bohon/56%20Chevy%20truck/BrokenTO001.jpg[/IMG]

But this could have contributed to the trouble. The cage that the ball bearings ride in is made of plastic:

[IMG]http://i7.photobucket.com/albums/y261/bohon/56%20Chevy%20truck/BrokenTO002.jpg[/IMG]

1956 Chevy 3200