Used alternator adjuster spacer block, Mazda MX5 or Eunos Roadster 1.6 mk1.
The upper alternator mounting bolt goes through this and also the long adjuster bolt is threaded through it.
This is the early, square type, but it can be replaced with the later type which is the same as the PAS adjuster spacer, search for our part number UM00967.
F20118363. UM00526.