Sounds like a frustrating mixup. I'm not trying to question you, but I am just curious because I'm not an expert on the differences and am only going by what I've read, but I recall seeing that the 71-72 trucks have their own upper ball joint and tierod ends, and share the same lower ball joint as the 73-up trucks. So if those spindles fit on your truck (minus the tierods), how could they have been pre 71 spindles? I read the 73-up tierods share the same thread as the 71-72, so maybe it is possible that someone along the way put the wrong tierod ends on your truck and then reamed out the spindles to fit? Again, I'm not sure, but just trying to give some other thoughts to help clear things up. By the way, I got all my info from a very good FAQ written by lolife99
here.