@dnc1 thanks for the info. I wonder if the unmarked Campy one I saw was a 3 spd part. It was the most expensive one anyways ($175), compared with the Campy 5 spd and REGs which were $70-$90. Now I wonder if the REG would still work for the 4 speed if the 3 spd Campy won't, but the REG works for your 3 spd.
Do you know why the 4 or 5 speed Campy versions would not work for your application?
Not being able to see it, is your REG their 5 (or 10 I guess) spoke design?