Hard to answer that exactly. The sensible thing to do in getting an ms251 is to get the dealership to swap out the 0.325 pitch chain bar and sprocket for the mini spline kit and 3/8 picco set up. It came up $7 less for me. Might as well get the 18 inch bar and use 62 links with the 7 tooth drive the sprocket kit comes with. Yes those smaller Stihl bars the 3005 series have less drive link count than the 3003 at least in "18 inch" and 0.325. Even if you later choose to use 0.325 chain just get a different drive sprocket, about $7 from Stihl and a narrow kerf 0.325 bar and chain about $30 if you shop around. "wood boss" seems new in this model, wonder if that means lower grade bar than before. My 18 inch picco bar was made in Germany, not sure what you will get now.