I just picked up a low hour Honda GX610--got her running yesterday, but learned the seller didn't include the regulator/rectifier. He's going to look for it, but since the engine sat for several years I doubt he'll find it.
New ones are stratospheric in price-- $120 is about average.
I believe the Honda part number is 31620-ZG5-023, which supersedes to -033. It's a 20 amp regulator with a pigtail or socket with 6 male spade connector inside.
Used is fine, or, recommendations on an acceptable substitute would be greatly appreciated.