I'm not saying this article is the final word on the subject. I've found that "absolute truth" is hard to find for 356 ABC Porsches. What I am saying is: "here are the facts as they are presented in the factory reference materials I have" (see list at right).
In the 1955 Pre-A parts book, Porsche lists three (3) separate headlight assemblies: Bosch (644.631.101.00), Hella (644.631.101.01), and Hella sealed beam (644.631.101.31). It also mentions that the Park Light and Blinker light were one unit (meaning the little white beehive light in front). I haven't seen a blinking headlight assembly, but who knows. This seems to rule out park lights in the headlight assembly. The rest of the 1955 parts book seems to verify this as there are no other Park light parts or assemblies listed. From comparing part numbers to those in later Porsche parts books, it can be deduced that the Hella sealed beam was probably intended for USA, the Hella was probably for right hand traffic countries, except USA; and the Bosch was for Left hand traffic countries (England, for example).
In the 1957 356-A parts book, Porsche lists five (5) separate headlight assemblies: all three listed above in the 1955 Pre-A parts book, and two new ones: Bosch Asymmetrical (644.631.101.02) and Hella Asymmetrical (644.631.101.03). In the 1957 parts book, it also mentions that the Park light and Blinker light were one unit for Coupes up to chassis #100,000, Cabriolets to #61,700, and Speedsters to #83,200. Subsequent chassis numbers for each model had a separate blinker light. There is no listing for a park light, either separately or in conjunction with the headlight assembly. None of theses 5 headlight assemblies is shown in the part diagrams with an integral park light nor are other parts/bulbs listed for park lights as part of the headlight assembly.
In the January 1960 356-B T-5 parts book, Porsche again lists three headlight assemblies: Bosch (644.631.101.00), Hella sealed beam (644.631.101.31), and Bosh Asymmetrical (644.631.101.02). In this 1960 parts book, the destination differences are clearly stated, i.e. the Bosch (644.631.101.00) was non-sealed beam for left hand traffic. The Hella sealed beam (644.631.101.31) was for the USA. And the Bosch (644.631.101.02) Asymmetrical was non-sealed beam for Right Hand Traffic, except USA. Here again, the parts drawings and subsequent listings do not show Park lights integrated into the Headlight assembly, EXCEPT for the "Bosch (644.631.101.02) Asymmetrical for Right Hand Traffic, except USA, non-sealed beam". This unit utilizes a non-sealed beam bulb, and the parts diagram shows a small 4 watt additional bulb as part of the headlight bulb assembly. It is not stated specifically that this 4 watt bulb is a Park light, although no other use makes sense. It would have been available for right hand traffic countries, EXCEPT USA.
The September 1961 Parts Book Supplement set for the 356-B T-6 makes the following comment relative to headlight assemblies: "No modification", probably meaning that the same headlight assemblies were used in the T-6 as in the T-5.
And lastly, the parts book Supplement set for the 356-C, dated August 1963, indicates usage of the same three headlight assemblies: Bosch (644.631.101.00), Hella sealed beam (644.631.101.31), and Bosch Asymmetrical (644.631.101.02), as for the 356-B T-5, with the addition of a new Bosch Asymmetrical (644.631.101.07). As before, the Bosch (644.631.101.00) is non-sealed beam for Left Hand traffic. The Hella sealed beam (644.631.101.31) is for USA, and the Bosh Asymmetrical (644.631.101.02) is non-sealed beam for right hand drive, except USA. In this parts book supplement, the front Blinker light and Park light (now called 'Side light") are integrated into one unit.
A. There seem to be three (3) general types of headlight assemblies: (1) a standard non-sealed beam unit for right hand traffic countries (driving on the right hand side of the road), EXCEPT USA, (2) A sealed beam unit for USA, and (3) an Asymmetrical non-sealed beam unit for left hand traffic countries. Note, a right hand drive car drives on the left hand side of the road, and the headlights are aimed slightly to the left.
B. There are three general designs of the "glass lens" for these assemblies which correspond to types of assemblies. (1) the standard non-sealed beam unit for right hand drive countries, except USA, has a fluted/sculptured lens with vertical lines and a circular pattern in the center with a triangular shaped fluting on the right side of the lens (looking at the lens head on. (2) The sealed beam unit for USA has a clear lens with some fluting/lines only in an arc at the top, and (3) the Asymmetrical non-sealed beam unit for left hand drive countries has a lens that has a fluted/sculptured lens with vertical lines and a circular pattern in the center.
C. The parts books (collectively) do not show, either in the part diagram drawings or in the part descriptions, any headlight assemblies which include the park light, EXCEPT for the Bosch Asymmetrical (644.631.101.02), which was a non-sealed beam unit for right hand traffic countries, EXCEPT USA. This would suggest that a headlight assembly with integrated park lights was available for right hand traffic countries, except USA. The parts books indicate these were available for the 356-A's through the 356-C's.
D. It would appear that the only headlight assemblies that contained an integral "park light" was the Bosch Asymmetrical (644.631.101.02) which was a non-sealed beam unit for right hand traffic countries, EXCEPT USA. If you have one on your car, it is likely that it is a Euro-spec car (Not Great Britain), or that somebody changed the lights somewhere along the line. Or maybe you have VW headlight assemblies! Cars built for USA had sealed beam light assemblies, going back to at least the later Pre-A cars, and according to the parts books, they clearly did not have integral parking lamps.
Lots of circumstances can affect what is in/on a particular 356, either at the beginning of its life, or as it is right now-today, but I also tend to take the "parts books, workshop manuals, and owners manuals" at face value. They do set a standard: they represent "documentation" for a particular way of doing things at the factory, and they are an official statement by the factory of what they did on day "ONE" during the construction of our cars. Of course any of these parts could have been changed in the 35 to 55-plus years since our cars were built. The above are the facts as I found them, draw your own conclusions.