thrust bushings
 

does anyone know what would cause the thrust bushings on the crank to fail and what the signs are?....thanks

The thrust bearings on the crank are usually just a specially shaped crank bearings. They are lubricated with engine oil so any oil failure would cause excessive wear on all bearings I woud think. Signs of worn bearings include low oil pressure. There may be others I am not thinking of. As for causes of thrust bearing wear specifically I would suspect pressure inward on the end of the crank. From the transmission end I would expect the symptoms to include difficulty shifting if there was something wrong on that end.

Of course I am not a real mechanic, so please wait for a professional opinion.

Where's Bob when you need him?