Connecting Rod Mystery

It was to add weight and material, ford does it alot, but not as common as mopars. Working in a machine shop I get to see all kinds of different versions, In our rod room theres at least 1000- 2000 sets of rods, anything you could think of. And the early 70's 318's that were floating were the "light" duty rods- not as strong, skinny beam.