LRDG Chevrolet Truck Fuse panel for No11 wireless set

[Charlie Down]

I have been researching details of the Long Range Desert Group and have come across an interesting photo with a detail I haven't seen before. The photo shows a Radio truck of T patrol in 1942. As you know these Chevrolet trucks were fitted with a No 11 wireless set for transmitting and receiving signals, and a civilian Phillips 635 radio receiver for the GMT time signal for accurate navigation using the stars. In the photo there is a black panel behind the drivers right elbow on the far right of the photograph. On the panel you can make out the word 'SET' which I believe in full would be 'Set No 11'. It looks like a fuse or power panel of some sort, most likely linked to the battery stowed on the running board on the RHS of the vehicle beside the driver. Having seen this photo I have found other photos showing a panel in the same area. Non radio trucks don't have this panel and I have been unable to find out any information about it.
What is it?
Is it a standard piece of kit or a panel made solely for the LRDG.
Are there any other photos and dimensions of this panel in use with any other vehicles?
It's a very intriguing photo and feature.