Working on fixing this ongoing squeal problem on my jeep, examining where the front shaft goes across to the wheels, but before the joint are. where it comes out of the case is a plastic ring. on one side It was tight against the case, on the side the sound appears to come from it was slid out. I though it could be loose and causing the noise, who knows?! ive been looking at everything I can. tapped it a few times to move it back in, and being cold out the plastic broke on the first tap. I just want to know what this piece is, and if its important. I imagine that it just keeps dirt and debris out of the case, so its important but not gona kill my jeep now. I was gona super glue and put it back on, but I am missing a smaller piece.