I understand that the "AT" means it's a replacement engine from Porsche, but why are the rest of the digits missing?

 

Made in China.

 

Congratulations on your receipt of stolen property?

 

Not sure if serious or joking....

 

Stolen Chinese motor

 

If you knew me you would. Of course joking.

I'm puzzled myself. Weird.

 

The S/N on mine was stamped dot-matrix style so lightly that I had to wipe it down, then look very closely with a light shining at an angle in order to see it. It's hard to tell if yours is even there at all. You could try using some grime to try and fill in the digits, then wipe it off lightly, exposing them.

 

Engine was never designated to a specific car, just rebuilt for replacement duty.

 

Mine has AT in it, but I still have a serial number. Does this mean it is a remanufactured motor specifically for my car?

 

All the ones I've seen has the dot matrix style script. The block that OP has seems a bit suspicious...

 

Your engine was used in a murder so numbers were ground off.
Seriously clean it off bet you'll find them

 

EXACTLY what I was thinking!

 

I'm starting to believe this....

I did this with some black grease and there isn't any other script on the tab/plate. I had the IMS replaced with an LN and a double row came out so it's not a newer rebuilt motor with a single or big bearing. I'm guessing this means it was rebuilt many years ago.

So strange.

 

Another hypothesis: Could it mean that the engine was remanufactured around 99 or early 2000, hence getting the dual row which was pretty well all you could get as an IMSB at the time?

 

Does the case have any blue paint on it?