[SCOTI]

I would try 71-72 parts & see how they seat vs. what you currently have. This would be my investigative progression:

*Purchase a new upper & lower BJ for a later model truck from a local parts store (71-72 and/or 73-80).
*Pop each end loose @ the spindle on your truck & compare how the later model stuff seats into the spindle vs. what you currently have.
*If they fit better, you now have to decide if you're going to replace them.

If they don't fit any differently, you simply put the new parts back in their respective boxes & return them for a refund.
If they do fit better, my guess is a mis-boxed set of spindles.