Hi mtnman, Not for sure. I just paired with 681 engine. The info I came up with, that engine had a 6-wheel tender. I guess it's got to be a 2426W or a 2671W that you mentioned in your replay. I could post a picture, if you would like to see it. I have looked it over many times and there is no number amy place on it. I guess it cot rubbed off somehow. Dockside