Everything should bolt right in. Both 1/2 and 3/4 tons used the optional 500# springs. I'm not sure if your frame rail would have been factory drilled to accept the mounting brackets. I don't understand what you mean by lower brackets though.My C20 is factory equipped with this set up and just has wear pads on the end of the axle control arm where the leaf comes in contact. If you need photos or anything send me a PM.