I had the same problem with rattles coming from the back, sort of a vibrating buzzing sound that would become louder over bumps and road irregularities.

When removing the engine cover I found the torx screws loose, not even hand tight.
After cleaning the engine (getting ready for Tess Tickle's clear engine cover) when replacing the cover I tightened the screws and ...... NO MORE RATTLES. Hope this helps someone.