I also have the back for my set, I haven't examined it super close lately but I don't ever remember seeing any sign that a metal cage was missing from the back. I don't have a photo of the back of it saved but you can see from this photo it lays flat, no metal back. Maybe between the 105 production and 106 they switched design? My chassis is dated Oct 26, 1948, when was the 105 chassis built that had the metal hv cage?
