Lately my jeep has been making a rattling (metal on metal) sound that clearly is comming from the bell housing area. It does it intermittently, and sounds exactly like my exhaust it rattling but it's not. The clutch, throw out bearing and input are LUK with 6000k miles on the assembly, the slave is new complete replacement with 6000k miles on it. The transmission is a 1995 ax 15 with 150k miles (my second one) and shifts perfect. What could be making this noise without affecting the operation of my transmission?