I have all of the parts necessary to replace the timing cover to block gasket on my 1977 4.6 P38. Since I have to pull the oil pan to accomplish this task, I have a question. The Range Rover has 173000 miles on it. There is a very light no load knock (only I seem to be able to hear this) when the engine is cold. Should I replace the rod main bearings while I have the pan off, it looks like it wouldn't be that major an issue to do at that time, or am I possibly risking causing more problems.