Sorry I gotta ask because you didn't say. Is this with a good working power steering pump that has fluid, and with the engine running, and did you bleed the air by going from lock to lock a couple times and add more fluid? Did you set up the power steering gear adjustments for thrust bearing preload and over-center preload yourself, or just use the steering gear as-is out of the box? What year is the power steering gear made for, I've heard that 67 is a different thing compared to later years, so wonder what is your setup. The adjustments are mentioned and excerpts from the manual in this other thread:
http://67-72chevytrucks.com/vboard/s...d.php?t=812162