I respectfully disagree about where that seam rides. I have roughly thirty auto-trans motors and look over the back of my little boat all the time. The seam might be in spray but it is not in solid water, at least not on 12 foot boats. Also, auto trans motors are such a pain to do a pump on properly, and the impellers are so susceptible to taking a bad set, that I feel anything I can do to make them last even a bit longer, is well worth it.
Long live American manufacturing!