[Bob's 70c-10]

Hello, I'm new to the site and I have a question that hopefully someone can help with. I have a 68 K2500 and I'm doing a p/s conversion. I have all the necessary parts including a captionfab plate (excellent piece highly recommend) to mount the box, but what I need help with is some measurements as well has any important advise about the placement of the box on the frame. Any help would be greatly appreciated. As well as links to threads that have done this on a 67 or 68 4x4
Thanks
Bob