Hans, we are finding more all the time in junk yards. Ray found a yard with dozens of non-registered Squarebirds just last week.
So, are you asking about how many are still on the road and registered? How many were produced? Simply asking how many there are isn't valid because some are being restored right now while others are sacrificed as parts cars or scrapped. Others still, are on ice in barns or laying in fields all over the world. - Dave