I have a 97 M6 and when i let the clutch out it starts to rattle really bad and i think its the pilot bearing. How much does a new one cost and how easy is it to replace? Do i have to pull the tranny or could i just slide it back on the shaft?

 

The pilot bearing only turns when the clutch is disengaged...IE, clutch pedal to the floor. More likely the tip of the trans mainshaft where is goes into the trans input shaft is worn.
Doug