KD engine stamping

[Rod R Youssefi]

My understanding is that the KD stamping is an engine that was replaced by the factory. Did the factory restamp the original engine number after the KD stamping or is it a different serial number? Also, compared to an original numbers matching engine, how much does the KD stamping effect the value of the vehicle?

[Martin Benade]

As far as I know they added KD before the existing number of whatever engine got rebuilt. The KD referred to the fact that it was rebuilt by the factory. It was then installed wherever, such as a dealer, or maybe cash and carry. Usually those engines would not be considered numbers matching.

[Doug McDonnell]

Lots of previous discussions. From them it seems KD means changed at the factory. AT engines probably at the dealers. I know Stoddard sold remanufactured engines complete years ago. The 2nd owner of my car bought one. It was an AT engine and came in my car with the original engine separate sitting inside where passengers seat would be when I purchased it. KD will be mentioned on Kardex. AT will not. Since the Kardex was a factory warranty card. KD was not just stamped in front of the original number. See Attached Kardex with original and KD engine numbers.Sorry but I don't remember where I got this Kardex photo.

[Ron LaDow]

[...]Also, compared to an original numbers matching engine, how much does the KD stamping effect the value of the vehicle?

This or similar questions come up regularly.
Here's a pretty clear answer (no snark, Rod): You asked how much it affects the value, therefore it does.
Your question alone tells me you find some reduction in value compared to one where there is no question at all: Here's the car, that's the engine and here's the COA. No question, no story.
And the same is true of anyone asking the question; if there is a question, there is a question. Buyers bid less when there is a question and the accompanying story.
Regarding how much, I doubt anyone can answer that in a general sense.
I'll believe it doesn't matter when someone with a numbers-matching car offers it without mentioning that.

[Edwin Ek]

KD stands for Kunde Dienst. In English that is customer service. AT stands for Austausch, or exchange.

Say, if in 1970, you took your car back to the factory for an engine rebuild (using your original case), would the mechanic stamp KD in front of your original engine number?

Were AT engines rebuilt by the factory or by dealers? I remember Stoddard selling rebuilt engines in the 1970's with AT stamped.

Brad Ripley surely knows all about this; I bet he has addressed this before ...

[Vic Skirmants]

From what I can gather, the original engine number was used, even if on a later replacement case. And of course the KD stamped in front of it.

[David Jones]

VW used the same system and in 1967 before I returned to the UK after serving three and a half years in the RAF in Germany I bought an exchange engine for my 62 VW bug. It was stamped KD and it came from the factory. I drove in to the dealer on a Saturday morning and drove out with my new engine before lunch.
I had to junk that car in 73 because of rust and failure to pass the UK road test as a result.

[Rod R Youssefi]

thanks for all the input guys

[Martin Benade]

Did people ever get their own original engine back, rebuilt and KD-stamped? Or was it always some other engine?

[James Davies]

From what I can gather, the original engine number was used, even if on a later replacement case. And of course the KD stamped in front of it.

Doug is correct above. Sometimes a new motor with a new number was used, especially if the engine was replaced years later. I've seen pre-A Kardex documents that show the original engine replaced by a different Porsche engine, marked KD. Here's a Kardex of a 1954 coupe with 2 different KD motors listed, both with different numbers. The KD motors are the "then current" Porsche motors in production it seems.

[James Davies]

I also know that people have forged (restamped) lots of blank cases over the years and have used "KD" stamps on them to cover their tracks. From my view, the only way a "KD" motor could be considered adding extra value to a car is if it is documented on the Kardex or COA. Otherwise it is just another replacement motor with a "just-so" story.

Of course there is nothing wrong with a replacement motor. But if you care about matching numbers and what that means for the provenance of a car, then don't be fooled.

[Doug McDonnell]

I have read that the factory changed from using KD stampings to AT stampings somewhere around 1970. But I have never seen any factory literature verifying this.