RIGHT ANGLE  STEWART WARNER TACH DRIVE  SW651XR333X4  TACHOMETER  DRIVE NOS

 I guess I would call the part sticking out the input that's what would attach to the tech distributor.  When you turn it 3 times around the other end goes around 1 time.

ONAN 302-0756

FITS ONAN MODEL DYG GENSET

Casting number 420 238

SW651 X R 333 X 4  TACHOMETER  DRIVE NOS

New old stock from long term Onan factory surplus
No box.