Engine or PTO HP on the engine plaque?

[careyo63]

I've done it for yrs. just saying 5Eng. Hp. to make 4PTO. Hp. And have always been close if you use a standard US. rated plate

 

[HoyeTractor]

The only one that I've noticed that doesn't seem to follow the 'rule' is the YM3110 / YM336. The 3110, according to the 1.2 rule, would be 37 horsepower but the 336 manual says it is 33hp. Not really sure what is going on there. Maybe the 336 was derated?