Did you remove the center link and re-install it?
Sometimes people get the center link backwards. I understand this will make the truck drive and steer incorrectly.
The tie rods should be on the backside of the center link with the castle nuts facing the front of the truck.
Here is a thread.....
http://67-72chevytrucks.com/vboard/s...d.php?t=400205
Just wondering.