Does anyone know where on the 10 inch circle dimond plate the spider legs are mounted. I originally thought it was in the center, but by looking at the pictures, it is near the bottom. But there is no specific instructions regarding this information
Check the Official FIRST Field Drawings. In particular, look at Field Rack Fabrication (sheet 2), which shows the details of the Spider Foot (including the location of the mounting holes), and Field Rack Sub Assemblies (which shows how the Spider Foot mounts to the Spider Leg, including the off-center mounting position).