Wow! Check out our one piece 10 inch step notch. These are constructed of 2 x 4 inch steel with a 1/8" (.125 inch) wall.  Our weld-in 10 inch one piece notch will give you the axle clearance you need for your lowered truck.  A step, or "C" notch is required to get your truck lower to the ground in the rear.  After installing, your rear axle will be able to travel upwards 10 inches past the original location of the frame rail where you would normally bottom out! This is installed by welding it to the rear frame rails directly above your axle and then cutting the frame between the notch area.