Just finished building my 2x72 cone sander and the last piece was the plate. The plate itself is fine, but the screws are metric, NOT 1/2 inch. DO NOT attempt to fit 1/2" wheels on it unless you like the backlash and loss of belt speed.
Pros
Axial holes are 10.5 inches center to center; By mounting two 2" diameter wheels on this backing pad, you can easily fit an 8" long, 2 1/2" wide flat plate between the wheels for a large sanding area.