If installing the skid plate over the DEF tank AND you have the Rockhard rear bumper, it will be easier down the road if you ever need to remove that skid plate to cut access slots in the bumper where the two flanges attach. Otherwise you will need to remove the bumper and tire carrier (if installed) just to get at two bolts. You cannot just drill two holes as there is not enough room to slid the flange out from under the bumper. So just cut an access in the bumper about 75% or so the length of the flange and 100% of the width. This will return it to the 3 minute job that it should be rather than a couple of hours and the help of someone else to remove the bumper, especially if it is steel. Don't forget to prime and paint the cutout as it will rust as it is steel