"AT" engine number

[Pirulero]

Good morning,

I need someone that can explain me one particular detail I found this week.


I have a friend with a 1974 2.7Carrera MFI Targa.

The serial number stamp is : AT * 664....*

The stamp style are 100% perfect and original.

What does AT means??

I remember that AT was the code for the engine that were changed by Porsch during the warranty period of a new 911, so in the beginning of her life.

Can someone confirm this?? Or am I wrong?


THANKS

[L.a.Brooks]

Porsche switched from the earlier "KD" stamp they used on 356's 911's and 912's to "AT" in 1970. Not sure why they changed from KD to AT. They both signify that the engine was replaced by Porsche and therefore usually noted on the Kardex.

[928cs]

AT means Austausch (=Exchange). The original serial number is kept but AT is added.

[Pirulero]

You confirm my opinion

Thanks!

[fourteenten]

Same goes for the gear box when replaced by the factory.

Cees

[preS]

AT means Austausch (=Exchange). The original serial number is kept but AT is added.

Does this mean that you got a "new" gearbox w/ AT followed by your old (matching) gearbox number?

Richard

[L.a.Brooks]

Usually they just put the letters (KD or AT) before the serial number on an engine that they had in stock. I suspect these might have been engines that had problems when they were first tested so Porsche repaired them and used them for replacements as needed.

KD: kunde dienst or customer service
AT: austausch or exchange

I've included a copy of the COA for one of my 356s. It shows the original number and then the replacement engine the factory installed on Dec. 12, 1970. The interesting thing is the COA shows KD730232 but the engine is stamped AT730232. This re-enforces my belief that they made the switch from KD to AT at about that time and the person entered the earlier KD version on the Kardex in error. You will also notice that the engine they installed was actually almost 2000 units EARLIER than the one my car originally came with. Certainly points to my other theory of where these engines came from. I've noticed the same thing on other COA's where the replacement engine was made significantly before the original engine.

[fourteenten]

Richard,

I think so only I can't read the numbers anymore after AT and I don't know when the gear box was changed either. Need to do some CSI and try to decypher what is left of the number.

Cees