NavList:

Kevin
My feeling is that this is a test piece which never went into full scale use.  It’s a bolt-on device, possibly for the rearwards facing ‘dogs-body’ third crew member of something like a B47 or a Navy A3 of which there were many versions of each.  The prism in the head appears servo operated from the controls on the front panel, or maybe even just car speedo type cables.  You can see the light path inside the bit at the rear looking like a vehicle exhaust manifold.  There will be a mirror or prism at each corner.  The device might not be primarily a sextant.  It might be an astro compass for tweaking the heading of a simple directional gyro or an early IN system.  It might simply be a periscope for the ‘Offence/Defence Guy’ (red Oleo painting the wings glows brilliantly in the setting Sun), or even a rudimentary method of pointing a couple to tail cannon to frighten inquisitive fighters away although why have a stopwatch holder and an averager.  You might find the attached interesting https://thanlont.blogspot.com/2016/02/a3d-skywarrior-third-crewman.html although the guy in the photograph appears to be holding a normal Kollsman. DaveP