You have a pilot model with Auto Pilot relighter and 110VAC Screw-in Heating Element. The Auto Pilot relighter (black box in top picture) was not original but added later. Model number would have been GC6AA-8E if it had been original.
A 110VAC Screw-in Heating Element located on the rear of the water heater. There is also a switch on the rear of the unit.
After manually lighting the the pilot light, the Auto Relighter (black box with wires in your picture) is used to automatically relight the pilot light if it is blown out. I believe this is a 12VDC device though Atwood documentation is clear in this regard.
You will have to trace the wires a bit for the wall switch as it could be wired for either of the following:
1) Turns the 110VAC Screw-in Heating Element ON/OFF
2) Turns the Auto Relighter ON/OFF
Installation/Operators Manual: http://www.atwoodmobile.com/manuals/...2011.19.07.pdf
The manual also talks to relighter operation