Hey all, hope someone may be able to help. I have a really strange rattle/knock coming from roughly the passenger footwell/gear box tunnel. The knock only seems to appear when my mother sits in the passenger seat! It doesn’t happen when there is no weight on the seat and also doesn’t happen when someone heavier sits there. I thought it may have been the rails or the bolts for the seat but these are all sturdy. Lifted the gear stick gaiters off and had a look around in there and can’t see anything obviously loose. The sound is like a light knocking and is not linked to speed or anything, more linked to the truck going over small bumps or swaying back and forth. If anyone has any ideas about this, let me know! 
