the clutch beel noise u are hearing could either meen that the bell is come away from the gear on teh bell (if it is a stock clutch bell) or it could be the bearing thing inside the clutch bell has broken or the screw that holds the clutch bell on the crank shaft has come loose. or infact it could also be your flywhell that has come loose. (if none of those then there could be a stone stuck near the flywheel and it is hitting it, but theres not much chance of that )

there is a pick of where to shimm the diffs a little while back. but if u cant find teh pic the shimms go between the bearing and the 38 tooth gear.