As shown in the photos there is a different shaft connection for the older style Arita butterfly gearbox shafts. It was changed about 3 years ago to make it easier to actuate a square shaft as opposed to round key slot. The round key slot shaft requires a key to fill the gap. If the gear box is ever removed there is no chance of losing the shaft key with the square shaft design.
The one pictured was replacing a 600mm Arita butterfly valve with a 1 metre long extension shaft to have the valve operating clear of the pit that it is installed in.
Midwest Valves & Controls continues its record of supplying these valves for industry.