I did not have to modify anything. The bracket does NOT go on top of the frame. It fits inside the rails. I was so excited when I put it in that I did not get a pic of just the bracket attached. It uses the same holes and the bolts drop down from the top of the chassis rail and the cab bracket is no problem.
Here is a pic I just went out and took for you. Its cold and I only shot one pic but I think you can see what you want to know.
If you call PirateJack ask for Tammy. She is very knowledgeable and tell her Alvin said to call her. Tell her I was the one that mentioned giving Stovebolters a discount and she may fix you up. She sent me some cards that had "15% off printed on the back of them. Let her know this and she will probably give you a good deal. Mine complete kit was $207 delivered to my front door.
http://i140.photobucket.com/albums/r19/LutherParris/52Panel/000_0202.jpg