I ordered some parts last February from Mastry Marine in St Pete's, including two cooling water pump impellers. I did not discover until last August that there are two different sizes of impellers, depending on how old your engine is. As it turns out, my engine takes part number 124223-42091 which is item 9 on the Yanmar Parts list and is shown on the first pump blowup. This impeller is slightly larger than the one they sent me which is part number 104211-42071 which is the replacement number for 104211-42070 and shown in the second blowup of the pump. Are you all confused yet? As it turns out the shaft, impellor and the seal changed in later models of this pump. I was hoping there is someone on the forum who may have the same problem as me only having received the impeller I need in which case I would be willing to switch. If not, I would be willing to sell them at a fairly deep discount. I can be reached at heartofoak1@hotmail.com. Reg