I'm on the hunt for another Simplex SX410, 610 or 630 rear derailleur. These are nice derailleurs that work well and don't break the bank like the Super LJ's.

My question revolves around other derailleurs that would work. The Simplex models I'm looking for are the ones that go into the non-threaded dropout and have a bolt that threads into the derailleur from the inside of the drop out.

What other derailleurs would work? I've seen a Spidel with this set up. Did Huret make any? I guess I'm looking to broaden my search for potential candidates.