Here is the problem. When the SUV gets a little warm... It starts this knocking. (See video)
It sounds like its coming from the item in the video.

Thanks for any help!

 

I believe those are the catalytic converters. The substrate in one of them may have broken loose and could be the source of the rattle. Something you might check , make sure the flywheel flexplate is tightly mounted to the trans converter and not loose or broken.
Also, check the crank pulley (vibration damper) for the rubber cushioning broken loose.
There could be other possibles and hopefully someone will add them.