Things can be available but never taken up
The Viscount 840 for example
The Protoype 700 was re-engined and flown at over 400MPH for that version of the 810
But no one ever ordered it and the conversion kit option was never taken up by anyone....so despite it being available for sale for a few years it never actually existed.
I'm sure if a floatplane Islander was wanted they would have built that, but no one showed much interest in the mock up as was also the case with th BAe 146-STA
So it is possible the floated Chipmunk was there on paper.maybe ecen breifly trialed then converted back but not taken up by anyone
