I have it setting on the frame, it's a little short, about 3''. I'm not sure how far from the back of the cab it should be, I'm thinking 1 1/2" max from cab. My only concern will be if the fenders are going to fit. I will have to weld up the fender holes in the bed sides and redrill them in the proper spot. I will have to put the running boards on and see. Will keep my fingers crossed. I can always bob the rear frame rails off a little if need be.