Todd
First let me say that I am no Concours expert, and anything that I add to this subject, I will try to back up with refrence from others and photos that I have gleened from the web. If you look on page 93 of George A. Husseys' book '914 TECH TIPS 700' you will find photos of both european fog lights and US driving lights. Although these lights look similar, they are slightly different in physical appearance and size. The lenses are not interchangeable but they are both manufactured by HELLA of Germany.
The lenses of the euro fog lamps were manufactured in clear and yellow. I understand that the French 914's were the only european cars supplied with the yellow lens. I don't know if the yellow lens was backed by a yellow reflector. I doubt it, but maybe. On page 37 of Dr. B. Johnsons' book '914 and 914-6 Porsche, A Restorers Guide to Authenticity', you will find another detailed description of 914 driving lights and fog lights. He also indicates that the French lens was yellow and makes no reference to yellow reflectors.
The three photos that I have included show a set of the yellow french fog lenses (NOS), a pair of clear euro fog lights and a U.S. spec. fog light. You will note that the clear euro lens and the yellow euro lens are identical except for color. The photo of the yellow french lenses are an NOS set that I purchased on an eBay auction for installation on my '71' 914-6. I believe that I lucked out because they are almost impossible to find. The print on the lens reads as follows ....... HELLA 1-101289-02-MADE IN GERMANY
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