Ronnie Stensson, a Swedish Corvair owner, provided the following information regarding clear turn signal lenses:
Guus de Haan, a Corvair owner in The Netherlands, provided this additional information:"In Sweden, all Corvairs sold had white lenses. The Swedish law says that the parking lights cannot be amber, but the front directional signals can be either white or amber (newer cars, from 1975 I think, must have amber directional signals).
On the early Corvairs it was easily solved by putting the 1960-62 lenses (white) on the 1963-64 cars also. The lates had to have these special made white lenses though. From what I remember (from my two '65 Corsas I used to own), the text on the lenses were exactly the same as on amber lenses (even the article number), so they were made in the same "mould form".
I have never seen any lenses for sale at swap meets or such places, so they are quite rare I think. Apparently, other countries in Europe used the same lenses too. I own a '66 Monza that was imported used to Sweden when it was three months old. It never got any white lenses.
Instead, it has each parking light bulb inserted through a hole drilled from the backside of each other headlight (sealed beams were never allowed in Sweden, only headlights with separate bulbs)."
"The reason clear turn signal lenses were, and still are, required is that when the main (low beam) lights fail, the oncoming driver still has to be able to see a car is coming towards him instead of maybe a motorcycle."