Amazing find, Chris! I hope this is somehow saved or protected from furhter detoriation. I'm not sure it could be restored, but there can't be many of these left.
Here is a link with some info which you may find interesting:
"The Trailer APF (Accurate Position Finder), later sometimes referred to as Trailer, AA Radar No 3 Mk 1"
http://www.rcsigs.ca/index.php/CMP_Trailer_APF
"Radiolocation (Radar) Unit GL III(c)"
http://www.rcsigs.ca/index.php/Radio..._Unit_GL_III(c)
"Trailer ZPI (Zone Position Indicator), later sometimes called Trailer, AA Radar No4 Mk 1"
http://www.rcsigs.ca/index.php/CMP_Trailer_ZPI
"One of a series of photos showing the Canadian GL III(c) gunlaying radar. The photos are dated 26 Jan 1943 and show an early example of Radar (originally known as Radiolocation) equipment in then in use by 1 Canadian Radiolocation Unit. This photo specifically shows the electronics of the APF exposed for maintenance."
