You should be able to push a 54" blade pretty easily. I have a 54" Warn plow for my 650. Plenty of power. I don't see why a 400 wouldn't push it. Plus I wouldn't go less than a 54" cause that way when you angle the blade, it is still wider than your rig. A 48" angled will be narrower when angled and then you end up driveg on your windrow. The Warn plow is fairly cheap on Ebay.