Steve,
In the event ones finds the need to pin the bushing, what size rivet did you use?
With the outer bushing and arm being of steel, did you use steel or aluminum or does it really mater?
Jim, I don't use rivets, that was someone else, I drill and tap the arm and well into the bushing for a 1/4x20 allen/hex set screw, leaving it sticking out a few threads.