58011 Was made for Master Vibrator, Dayton OH for there tamper, rated at 3.5 HP @ 5000 RPM. 580 engines were rated between 3.5 and 5.0 HP depending on RPM. The Five port 580 was rated at 6.5 HP @7000.
The curve on the three port 580's is: 3.5 @5000, 4.0 @5500, 5.0 @6000.