Reverse swtich for automatic gear box (1978)

Hi guys, Im new to this forum.  Very nice to meet you all.

I have a 1978 Gls automatic gear box.   both of my reverse lights dont work when engaged  in reverse.. On manual gearboxes the switch is pretty easy to see and identify.

Sadly for this model I have no idea how this lights are engaged or where is the switch.

Any help will be great!
Thanks

As far as I know there isn't a switch on the transmission.
It is on the shifter control inside the cabin.

The switch should be on the shifter control.
There is a shorting bar on the shifter rod that makes the connection of the light in each positon that you select.

This shorting bar also activates the reverse lights.

Take the handle off the shifter rod
Then remove the cover off the console.

You should see a light assembly on the shifter rod.
Below it is a black plastic piece with a bunch of brass contacts in parallel to the rod.  As you move the rod you complete the circuit to light the light on the shifter rod to tell you which position that you have selected,  When you have it in REVERSE they also short the reverse light to illuminate your rear.  

It should be a very small allen key bolt/screw on the side of the lever. When reassembling make sure its not too tight and in the correct position. Also make sure that you can depress the side button and select all gears before using the car again before use.