Robin Subaru engines are identified by MODEL, SPECIFICATION, and CODE NUMBER. The MODEL NUMBER is usually the FIRST FIVE  characters on the tag typically starting with EY or EH followed by 3 NUMBERS 

For each model there may be many different versions called specifications. Each specification will be unique in some way. The difference may only be just the paint color or it may have a different type of PTO or some other significant difference but still a difference.  BE SURE YOU ARE ORDERING THE CORRECT PART REQUIRED.