Steve, I ordered my axle through the horse trailer builders who did the work. Nobody RV dealers would touch it because they don't employ welders. My builder welded the mounting brackets that were already attached to the axle to the frame as it was done originally. I guess I will be angry in another 36 years when I have to replace it. I sure hope there is still a frame to weld it to.
It is 22.5 deg down, leading. I've attached installed pictures, from front, from rear and welded to frame, and one as received from Lippert showing bracket and brake.