The question of which type of front turn signal assemblies were used for a specific time is sometimes clear and sometimes confusing, particularly for the late A cars. This article is an attempt to clarify the issue, but some aspects remain murky. This is because the 356 parts books are not infallible, but particularly because this part is easily changed, so only original owners with perfect memories can be certain of what is original to their cars. No attempt is made here to describe the front turn signal units used before 1954.
Brad Ripley has done a great deal of research on this topic, and his contributions are highlighted below in white boxes.
K3204, The "Early Beehive"
The photo at right shows What is commonly known as the "early beehive" turn signal unit was used from the beginning of the 1953 model year (October 1952) up to March 1957, according to Brett Johnson. The unit sits flush against the body, so it is tilted backwards slightly. Jim Breazeale has observed a variety of bezel types, with slight variations in thickness and in the style of the lettering.
Brad Ripley: The late (1954) Pre-A thru (1957) 356A T-1 unit is mounted flush to the body at about a 20 degree tilt upward. According to Parts Katalog notations, the lights had a white plastic lens and a 2-pole socket with set screw connection. The 11,00 mm thick chrome rim was marked K3204. The lens was 29,00 mm tall and no K-number was molded in.
Porsche part number was: 356 62 216
The "K" numbers were assigned by the University of Karlsruhe Lichttechnisches Institut (Lighting Institute), hence the "K" designation. Often the K-number has a sine wave ~~~ in front of the number. The light manufacturers (SWF, Hella, Bosch) would submit units for testing and the numbers corresponded to the position on the car with some sequence in the approval numbers.
K3215, Early Beehive T-2 Version
Brad Ripley: Similar to the T-1 version above, a unit was made with single pole socket with set-screw connection and K3215 on the rim and installed on the following non-USA cars:
Coupe 100000 thru 104090
Cabrio 61701 thru 150640
Speedster 83201 thru 85503
Porsche part number was: 644 62 216 .
K2665, the First "Wedge" Base
Below are photos of the SWF K2665 unit. This unit differs from the earlier type in that it has a wedge-shaped base, while using essentially the same bulb holder and bezel piece with the two screws that hold the lens in place. It also had bullet connectors instead of set-screw connectors like the earlier units. According to Brett Johnson, it had a taller clear plastic beehive lens than the previous units (the early ones were flatter and generally a frosted white color). K2665 may have been used up to the end of 356A production in mid-1959, but it was clearly not the only type that was used on the A model in 1959.
Brad Ripley: Probably to satisfy government standards, about March, 1957 a wedge-shaped (Keilsockel) chrome plated casting was combined with the beehive base. This arrangement allowed the light to be parallel to the ground and not tilted upward compared to the previous versions. The base had a single pole socket with bullet connection. The rim was thicker (13,50 mm) and marked K2665. The lens was taller (42,00 mm) and marked SWF K11442 molded in the tip. The Parts Katalog indicate this light was FOR USA ONLY and installed on the following cars:
Coupe 100001 thru 104089
Cabriolet 61701 thru 61892
Hardtop 150001 thru 150639
Speedster 83201 thru 84922
Porsche part number was: 644 631 401 00
2665, the First "Twist On"
According to Brett Johnson's Authenticity Guide book, a "revised wedge unit with a twist-on lens was first used" at coupe 104090, cabriolet 150640, and Convertible D 85503 (the beginning of the 1959 model year). It had a different, taller lens then K2665. This may have been the SWF 2665 unit (note there is no "K" associated with the number, photos of 2665 are shown at right and farther down the page) which did not have a separate bezel piece to hold the lens. Instead the lens had three tabs which were pushed into slots in the wedge base and turned slightly to hold it in place. Photos of SWF 2665 are shown at right (larger photos are shown below).
Jim Breazeale believes that, based on his observations, the 2665 unit did not appear until the beginning of 1959 (though at least one owner of a late December 58 car, 105901, reports it has the 2665 type). It is possible that both the K2665 and the 2665 units were used simultaneously for some period of time.
Brad Ripley: The final 356A version was an obvious attempt to make a streamlined one-piece unit. A single wedge-shaped casting was created to keep the unit parallel to the ground. A unique "one turn" (Bayonettverschluss) lens was incorporated, eliminating the rim. The clear lens for this unit was also used on the 356B/C lights until the end of 356 production (the same lens was also used on Mercedes 190SL and other models). The upper surface of the casting was initially marked K2665, the same as the previous "wedgie" light. Later, it was marked K12627 [see below]. Both these lights had a single pole bullet connection socket.
Porsche part number was: 644 631 401 01
K12627, Almost Identical to 2665
To further complicate the situation, sometime in early 1959 another type appeared with the same "twist on" style lens and single piece base but a completely different number. This type was stamped "K12627" on wedge base and the "SWF" was centered behind the number instead of in line with it (shown below at left). K12627 appears to have only been used on some 1959 (production year) A model cars. (Roy Mawbey reports that coupe 106954, built late March/early April 1959, appears to have come with K12627 units)
Steve Douglas believes that the German DOT required manufacturers to submit and list each regulated part (in this case lights) with a "K" number. He theorizes that perhaps Porsche started using the 2665 unit without DOT approval, and then during the 1959 model year was forced to change over to an approved "K" unit. This might explain why the 1959 model year cars had multiple front turn signal types.
Comparison photos of the SWF K12627 and an SWF 2665 unit are shown below. The units are very similar inside and out, except that K12627 is marked "18W" on the front of the base and 2665 is marked "15W", and the back side of 2665 shows "SWF 2665" and "372" (stamped in ink) while the back side of K12627 had "408" stamped in ink (not visible in the photos below, this is reported by Jim Breazeale and shown in this photo from him. Also, K12627 does not show the part number on the back.
Bill Leavitt reports that Porsche part number 644.631.401.06 appears to have been used for both the 2665 and the K12627 units, lending credence to the idea that Porsche considered them to be essentially the same. The only functional difference appears to be that the later unit was rated for a slightly higher wattage (18W vs. 15W).
K13306: One Unit, Two Bulbs
Starting with the B model in the 1960 model year, there finally appears to be some clarity! For the 356B and 356C, the SWF K13306 unit was used—dare we say it?—exclusively through the end of 356 production (photos below). For the first time the front turn signals had a left / right difference, that is, a right-side unit would not fit properly on the left side of the car, and vice versa. From the exterior, K13306 appears very similar to K12627 but it had provisions for two bulb sockets. US cars had two bulbs installed (because the parking light in the headlight was deleted) while European versions had one bulb installed in the K13306 turn signal unit because the headlight parking light was still used.
Brad Ripley: A feature of the new 356B model at the start of manufacture in September 1959 was a further refinement of the late T-2 light. Two main castings were used:
(1) the outer casting had two socket indentations cast in; the actual bulb contact pieces were riveted on the back side. This casting was shared with some Mercedes models. For Porsche it was marked with SWF K13306. In later production, after SWF was reorganized, there no markings. Also, the plating quality was not very good; those units came in white boxes with black print as opposed to the previous yellow and black.
(2) The larger inner casting was handed left and right (marked L and R on the back) and had no markings. Two lenses were used, a clear one, marked K13306, and an amber colored one for Euro cars, marked K13384. The amber lens started in June, 1961 (356B T-6) due to German law mandates.
The seal for the lens was an off-white sponge O-ring that deteriorated quickly. Present day seals are grey.
Porsche part numbers:
Left USA cars (clear lens) both sockets installed 644 631 401 05
Left ROW (amber lens) only the 18 w socket installed 644 631 401 06
Rights as above 644 631 402 05 and 644 631 402 06
Note: So called "Euro" cars continued to have the 4 watt parking light installed in the headlamp, so the socket for those bulbs was not installed in the blinker. USA requirements mandated the parking lamp to be in the blinker assembly, hence both contacts were installed. The wires for the Euro version were tucked back into the wire sheath at each headlight.
Warning to Swap Meet Devotees: there are many of the Euro blinkers on the market still in the white/black boxes. Before purchasing, take the lens off and check for contacts in the bottom of each socket hole.
SWF continued to manufacture the K13306 unit after 356 production ended, but at some point the later version changed to screw-on connectors, not the original bullet style. If you see "NOS" K13306 units with screw-on connectors, be aware that they are not exactly the same as those that originally came on the 356B and C cars when they were new.