Starting in ’29 along with the Sea Horse name, the Johnson bros started adding model numbers to some of their motors. The model numbers don’t represent the actual horsepower of the motor as they are usually slightly higher than the motors advertised horsepower. It could have been done to help boost sales as this was the start of the great depression era and new outboards weren’t a priority on everyone’s shopping list.

The only Sea Horse models which truly match the horsepower are the 3 horse A-45, or Sea Horse 3, and the 4 horse A-50 Sea Horse 4. The 4.1 and 4.5 horse A-65, 70, and 75 motors were also known as Sea horse 4’s. Another motor they branded honestly while holding a straight face was the 50 horse XR-55, or Sea Horse 50.

Some other motors with misleading model numbers are:

8 to 9.8 horse K-KD series which were Sea Horse 12’s.
13 to 13.3 horse S-45 thru 70 motors also known as Sea Horse 16’s.
The 20 to 22 horse P and PO motors or Sea Horse 24’s.
The 26.1 horse V-70 or Sea Horse 32.

I don’t think all of these motors had the model number on the tank decal as there’s supposed to be variations of the original decals used in each year. There’s probably more models than shown but you get the idea.