Shaft size ??

[Aquaholic101]

My current engine 225 opti has a 30 inch shaft on a 24 Proline Walkaround (2000) As I make calls to Yamaha, Mercury & Honda dealers on getting a new engine they all act puzzeled as to why I have a 30 inch shaft for a 24 Walkaround. I am the second owner and the engine is the original came wuth the boat when it was bought. I even called a Proline dealer and they are to get back to me ....still waiting. Could not find anything in the manual so I am wondering if a 25 inch would be fine. It would be nice as it is difficult finding 30 in as oppossed to 25 inch. Any Suggesstions?? Can I go w/ 25 inch