Anybody see this odd A/C dash vent system before?

Longest retrofit "knee-knocker" I've seen. My 1969 Dart slant had factory AC. As I recall, it had a similar bolt-on under-dash vent assembly, but the blower was inside the climate box. Mine was also purtier with chrome vents. Later, they moved the AC vents into the dash. The C-body factory AC had in-dash vents going back to at least 1965, plus some even had rear-AC units.