Of course attach the cable to the back of the scanguage. You can easily push the extra cable back in.
Next I just added some Velcro tape to the 4 corners of the gauge and the front bottom lip/ top inside lip of the box.
Put the top groove of the gauge into the top of the box, then angle down and make contact with bottom Velcro. Now this puppy is locked in via the groove. You can punch buttons and it is solid.
Here is overall view, showing the gauge at slight angle.
Yes, the doors are open so the floor lighting is on.
