You can not just randomly change the rotor and still have the rotor and caliper line up. I have yet to find any two factory replacement rotors for different applications be exactly the same and interchangeable. I have no idea what the height is of the rotor you are wanting to use. Then there is the issue that most later model rotors do not have sufficient contact area to accommodate the D52 pads without having them hang over the outside edge.
You know that I do make 2 rear disc brackets for the 6 lug correct?
http://www.67-72chevytrucks.com/vboa...d.php?t=637489
http://www.67-72chevytrucks.com/vboa...d.php?t=494411