heim is a spherical rod end (heim is one of the other names, as well as aurora, etc.). It is a threaded rod end that requires a tubing adapter (or tapping the tubing). Johnny joints (Curry's name brand I think) are a ball & socket kinda thing. They take the place of bushings in a spring. Also look into Orbit eyes from AOR, I believe they resemble the JJs.
As usual, I am no expert, this is just what I have learned from looking around.
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