[Buick455]

The attached photos of my 86 4x4 1/2 ton Silver ado frame clearly has the drooped rear cross member with holes. The frame also has cutouts in it which narrow the frame top and bottom members which is why I am not using this frame to build my 3/4 tone truck. I am using the 3/4 ton frame from my 87 which still has the dropped member but with no holes and the frame does not have the notched sections.

I would just removed the dropped cross member and build your own (or have one built). I would not build it like the ones shown that are made from round tubbing as this is good for keeping the members apart but may not be as strong as the original in preventing twist of the frame rails. If you use tubing the ends need to transition to the top and bottom of the rails like a "v". This transitions the moment/stress induced from the twist of the rails into the tubing. The only way to adequately design the member is to reverse engineer what was used and make sure the new member is as strong.