Hey everyone. I am new here and I own a welding shop in small town minnesota. A guy hired me to build him a new frame for his 65 GTO, and I got a couple books on frame meaurements, but there are a couple things missing. My 2 questions are... does anyone know what XYZ is in the 1st picture. And what exactly is the "o" line in the 2nd photo. Thanks in advance!