If you don't have an expert dealer for Yanmar, I recommend Gallery in Seattle. I'm a retired trailerable boat mech from Seattle area. I use them as I am retired in Kona. Their number is 206=547-2477. Make sure the impeller will slide freely on the shaft or it will not center in the cavity and may not pump. You could use this as a chance to replace the bearings and seal. If you need help, I'm at 808-333-5068.
Bob