OSU123

I have a 2005 f150 lariat 5.4L with 180,000 miles. Its been occasionally making a terrible rattling coming from what sounds like directly under the floor; so engine / tranny area. It most happens when stopped at a light, in gear, after the truck is warmed up. It appears to happen when ever the engine is under load and idling at low RPMs like when turning the wheel or put into first gear. It goes when when I rev it. Check out this video to get a better idea.

This has been going on for years but recently seemed to have gotten more frequent and louder. I have checked for all the obvious things that could rattle, i.e. heat shields and other loose parts.

Any ideas what it is?