On typical Unity spotlight installations not having the truck specific inside bracket, there is an angled rubber spacer that slides against the inside windshield post (or window frame or where ever the shaft enters the car), followed by a ring clamp that is in held in place by a set screw. In the picture below, the clamp is at 12:00, the rubber spacer is at 3:00, the ring at 6:00 has a loop that retains the wire after it leaves the handle, and the L shaped bracket at 9:00 is used to ground and anchor the spotlight shaft. The short end goes inside the square portion of the clamp against the spotlight shaft.
