That is the “transmission housing”. to fill, remove the inspection cover and fill with #62 Mobil fluid up to the small oil level screw located on the opposite side of the case. So says the Lauson manual. I researched the #62 Mobil fluid and found that it’s similar to a hydraulic fluid or a light machine spindle oil. I use the spindle oil in my motor, seems to like it just fine.
Joe B
PS, someone had posted the Owners manual here a while ago, maybe he wil come back with the link
