difference between k10 cab mounts??

[kidatheart]

I bought a k10 4x4 running gear and don't know what year it is. I know it is an '81 or newer. I am going to put a '79 body on it. When looking at cab mount kits, I am finding that '84 and newer is a different set than '81- '83. Part of the mounting hardware is still with the frame. I think I need the set that matches the frame. Can someone tell me what the difference is-what should I be looking for so that I know which set to buy? Thanks!