If you hear it from the rear with the windows down, it is the tires trying to break loose. These things have gobs of torque.
I have a bump under my feet when I am turning left or right. Had the same thing in my 06. Dealer replaced my cab mounts and it went away. Still need to take this truck in and have it done.
2012 F350 4X4 Dually, FX4, Crew Cab, Ultimate Lariat Package, Oxford White, Black Leather towing a 2006 LE3905 Weekend Warrior
2002 F250 CC, 4X4 - Sold
2004 F350 CC, FX4, loaded - Sold
2006 F350 CC, DRW, FX4 - Sold