I was always able to fix it by spraying all the moving parts with a ton of WD40 or something similar. One of my friends told me once that lithium grease is better and longer lasting, but I just never tried it. There is also a grease zerk in part of the clutch assembly under the truck. Its on a horizontal tube like piece. I didn't find it until last week. It was all covered with mud and stuff so I didn't even know it was there.
'73 K5
Chevy good...Ford bad