My truck had a similar bumper on it when I purchase it. Let me tell you that is was not fun to remove...welded very solidly to the inside of the frame rails. I cut the support of flush with the end of the frame rail and left the 1/2" thick metal welded to the inside of the frame rail. New holes and no problem expected when I bolt the factory rear bumper supports to the outside of the frame rails.

Rear bumper