Gauge assistance

Probably IS the instrument. Generally, you need to loosen the bolts in the floor plate, remove the small trim under the column, and remove the clamp bolts up under there. My 67 has 3. Remove the battery ground for safety, and "reach up" in there and unclip the speedo cable. Then remove the cluster trim screws and after dropping the column a bit for clearance, sort of hinge the cluster "down and out."