Replacing Porsche 993 Third Brake Light Bulbs with LEDs

When I purchased Ella, she was sporting a gap-toothed look on the 3rd (middle, high mounted) brake light.  This is really no surprise as the design uses 24 (yes, you read that right, 24) individual incandescent bulbs.

A quick search on rennlist revealed several others had the same thought I did: replace the incandescent bulbs with LEDs.  Even better, several options had already been tried and validated.  I just followed their lead.  Read on for the details and lessons-learned in my install.

[Update 12-Feb-2016]  I recently noticed that Tore at Bergvill FX is selling a kit to replace these incandescent bulbs with LEDs.  While I haven't tried this specific product, my experience with Tore has been great on other products, and I would use his kit if I was to do this job again.

1. Order ~30 LEDs.  I bought mine on eBay, and as of now, they are on sale here.  The specs given are "T5 74 37 70 Super RED Wedge Base LED Bulbs 12V". 
2. Follow the 3rd brake light uninstall instructions on pcarworkshop:  http://www.pcarworkshop.com/index.php/993_-_Repairing_the_3rd_Brake_Light

• I noticed that the rear half of the red plastic housing was cracked around every one of the five screws holding the two halves together.  I chose to superglue the cracks, carefully avoiding the screw holes prior to disassembling it.  Once it was disassembled, I applied additional superglue.  The rear pieces is not visible when installed, so no special care is required with the superglue.
3. Remove (with soldering iron) the 24 incandescent bulbs.
4. On the LEDs, straighten the metal contacts, pull off the plastic base and bend the legs to match the incandescent bulbs. Cut the legs to similar length as the incandescent bulbs.
5. Determine LED polarity.  Unlike the incandescent bulbs, the LEDs will light when installed one way, but not the other.  It doesn't matter which way as you can easily switch the leads when re-installing the light bar, but they do need to all be installed the same way.  I erroneously assumed all the LEDs would have the resistor on the same side of the diode and when I finished soldering them all in, 6 LEDs failed to light.  A battery can be used to test the polarity (they light even at 1.5V), however an easier way is to look inside the LED and you can see the structure as shown below.  
   
6. Solder in the LEDs.  You will want to make sure the LEDs are close to centered in the circle drawn on the PCB and that the height is similar to the incandescent bulbs.  This doesn't have to be precise, just close.  
7. Assembly is simply the reverse of the dis-assembly. Check the LED polarity as soon as you can connect the brake light to the car and switch the leads if necessary.

Before and After