A clock housing and wind-up clock (with a add-on dash light) was a GM accessory for 1954/55st Chevrolet truck. Accessories were not installed at the factory but they might have been installed by a dealer, or by the owner.
The easiest way to remove gauges is to remove the driver's seat so the you can spread your body over the floor. Any way you do it, you have to be a contortionist.
You might want to use some tape to number each wire before you remove it. Draw pictures and label connections points in the drawings with the numbers of the leads you have removed and labeled.
