I just went through the painful process of obtaining all of the mechanical clutch pedal linkage components for my truck. I started out with a mixture of '67 and '68-up components without realizing there were compatibility issues between them. I ended up with all '68-up components. I prefer these components because the "dog leg" pedal push rod gives more clearance for the rear header pipe. Here's a thread I started when I was trying to figure out what was going on.
http://67-72chevytrucks.com/vboard/s...d.php?t=847345