I have seen M1A1s w/TUSK 1 and a roller, buy no plows. As Rob said, they were not really used much in and around cities. The plow tanks were used to the west of Baghdad to clear mines and IEDs from the palm groves there. I believe it was around '06 when these pics were taken.
Also, as Rob says, the plow is heavy and may weigh the tank down too much with the TUSK. The roller doesn't weigh down the tank as much since part of its weight is on the ground, as opposed to the plow which is suspended unless it is in action.
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