To sum it up I was running the machine a while back and I could hear the rattling from the reverser to engine housing. It started getting worse and you could hear it rattle and knocking. After researching it on different forums, I realized it was the isolator. I pulled the engine and sure enough it was worn pretty bad so I started looking for the upgrade isolator and after quite awhile I gathered all the parts and reassembled it with the 350d isolator. I also noticed that the front reverser pump housing had witness marks on it which I figured was from the loose isolator parts. It looked like it was contacting the seal cover. I get it back together and when I started it up there is still a knocking coming from the bell housing. I have checked main bearings and all checked out alright. I also checked the old isolator and flywheel for witness marks from contacting the seal cover and don"t see anything. I am going to pull the motor again and before I do was wondering if anyone has any ideas as to the knocking sound. Thanks,Ken