[TerryW]

Terry. If all you need are nuts I would measure the stud and source the nuts from hardware supply. They are probably 1/4 28 or 5/16 28. They could be 20 pitch thread instead of 28. Get a couple of each!  Get a nyloc  locking nut.

The trouble is that they are stepped. So that about half of the length of the outside of the nut is round and sinks into the idler arm. I do have a milling machine, with a little fiddling around maybe I can machine up and polish some stainless acorn nuts from the home despot???