[Kaliv]

I was doing some reading and came up with a few ideas. But no, I don't have a definate answer for you, just some guesses.

One article I was reading said:

The first three digit numbers on the white label identifies for which market the car was intended. C00=Germany; C07=Italy; C16=UK., C23 Belgium.

Your first code was C02, which stands for the Catalytic converter option. So it's possible that the D29 is your market number...but I don't have any idea what market that would be.

Secondly, I read:

Porsche would always endeavour to provide what the customer wanted – however good or bad taste this might be. They employed craftsmen to create ‘ custom’ Porsche for their clients.

Usually it is to do with trim and finishes, maybe instruments with leather bezels, or leather dash, wood trim, colour coding, additional leather to the visors, headliner, wheel, car phones, even things like leather covered switches, seat buttons, flasher switch, and vents. Basically anything you like.

Porsche later claimed 'the most vivid imagination can become a reality’. And judging by some of the cars turned out they managed it!

So it's also possible that the D29 option was something someone special ordered, but because not too many people wanted it, no one recorded it down.

Also, I read:

The fourth digit on U.S. cars was the body style; A/B or C- Coupe/Targa or Cabrio.

I noticed that your 4th digit is "E". Interesting. Perhaps the article has some flaws, because your 5th digit is "B", and you do have a Targa. Then again in another article I read:

The fourth , fifth and sixth characters 'ZZZ' are fill in characters on European and rest of world cars

So that would bring me back to possibly the D29 is some country code in the ROW because your 4th number isn't A, B or C.

Food for thought.