I recently had to replace my transfer case. Of course, I'm always in a hurry, so when I removed the rear driveshaft I hastily threw the bolts on the ground near the stand so I wouldn't lose them. It was fairly dark so I didn't pay much attention to them. About a week later I received my replacement and proceeded to install it. Forgetting everything I did a week ago. When it came time to re-install the driveshaft I noticed that three of the four bolts to the universal joint were broken off flush. My first thought was that I must have gotten mud in them so I poked at it with my screwdriver and they were hard as could be so that's when I realized I must have broken the bolt heads off. I was disgusted with myself and tried to figure out how I was going to get myself out of this predicament. I needed the Jeep ASAP. Common sense slowly came back to me. I picked up the bolts to the yoke, and they were fine. ????? I then grabbed a scribe and gouged at the holes, and low and behold it gave way, and a yucky white larva emerged. I cleaned out the bolt holes and finished up the install. I just hoped to God that they didn't deposit anything in the transmission's shaft while it was left uncovered. So the moral of the story is to make sure that you cover up anything with a hole in it while waiting for parts.