i don't really understand of how you connect rocker guards underneath. i know you can put them on top of the body mounts but do you have to cut them, or can you just buy some special? plus i'm going to buy 5x5 angled steel and 5\16 thick,should i get something else or what, but i need it to be cheap also, any suggestions

5/16" is a bit to heavy, I would say 1/4" at the most. Run it from the bottom of the door opening, (6" on my 7), and whatever length under. You can have a steel shop bend the piece for you, then just bolt it to the tub. You can run it to the body mounts if you want, but that is a bunch of weight.