Make certain you are using this fork...GM Clutch Fork Assembly #839240 also the orientation of the throwout bearing. Whether it may have slipped off the fork or on backwards. Have you ever driven the truck with the old setup?
~ BD. "You won't find me in an old folks home" Pioneer Florida Cracker 1958 Apache Stepside 1958 Apache 1/2 ton Panel 1959 Apache 1/2 ton Panel