You did not indicate what year and model your vehicle is.  If your vehicle
is a splittie or baywindow you might find that the noise is due to a failed
weld on the front eighteen inch to two foot section of the clutch tube. This
is a guess as it occured on the old '57 single. Everytime that the clutch
was depressed the truck "groaned" like an old sailing vessel. a quick, clean
weld will help. Of course you should remove the cable prior to welding.  My
knowledge is limited to splitties and Vanagons. I am unclear if this
suggestion is applicable to the baywindows. It definitely does not apply to
the Vanagons due to the hydraulic clutch.
-ellis\