On the 6speed, there is a small metal piston that connects to the clutch and fits into an area in the lowe firewall. This piece rattles(metal on metal) unless the clutch in depressed a bit where it tightens up and cannot rattle. The clutch, when not depressed hits another cylinder looking piece that is adjustable. I adjusted this piece until it seems as though the clutch is depressed the slightest amount and no more rattles over there. This is difficult to explain however after you climb under the dash you will see what I am talking about. Jiggle the piston and if there is some play you will create this rattle. Of course you can verify by driving over some bumps with and without the slightest pressure on the clutch. I am not sure what the cylinder piece is that I turned a little to remove the play? Anyone know? Sorry for the poor explanation. I guess I can shoot photos if anyone is interested?
Hope this helps. And please if you know what these pieces are please add to the thread. Thanks!