Two questions guys: How do you tell if engine is 20" or 25"? What is actual measurement based on and I can tell by my model #, right? It is: 175FSXEC. Also, anyone have any ideas what salvage value would be if the engine is extremely clean and two cylinders are scored. I just dropped $500 on reseal of lower unit after some water was evident. Ive been told better to replace than repair.