2001 Monaco Dynasty rattle under passenger seat?

BIL's Monaco, yesterday going to the shop there is a rattle under the passenger seat or the

floor? We checked all bushings and shock absorber mounts, all steering mechanisms etc.

I sat in the stairwell as he drove and it sounds and feels like something is tapping the floor.

other than being a tad annoying on a bumpy road it's do able. Checked front compartment

and only thing in there is a rubber mat to wipe dirty feet.

Anyone come across something obvious? It resembles a loose shock absorber but that has

been all gone through.I wanted to slide out the genny but ran out of time, maybe something

there....