I tried searching for this and found no results. So my '02 5.9 has about 85,000 miles on it and a rattling has begun. It only happens when the truck is in park. Once I shift, the rattling stops. The rattling is irregular, not a consistent cadence. It's hard to pinpoint where it's coming from. Rear of engine bay, and below maybe? When in park, when I press the gas, the rattling goes away but returns under idle. No rattling in any other gears.

Thanks!