Trying to renew a junkyard rear end to replace mine that has a bent housing tube. Wasn't planning on gutting the diff but I dropped a C-clip and it disappeared into a cavity under the pinion gear. I spent about 6 hours trying to retrieve it. Finally gave up and removed the pinion and gear set. If your removing c- clips, make sure the diff is horizontal as if it was in the car. Mine was nose down on jack stands and I neglected to stuff some rags into the cavity. Lesson learned.