I have a 2001 a4 trans am ws6. please tell me what gear I have

 

Should be 3.23 (GU5) on the drivers side door. If you suspect they may have been changed look at a calculator like www.f-body.org/gears/ My door says 2.73 (GU2) but have 3.42's in mine.

 

Which A4s came with the 2.73s and which came with the 3.23s?

 

That will probably depend on the model. Like the WS6, Firehawk, regulay Firebird, regular Trans Am, Camaro SS, Camaro Z28 or base model. Also the difference between manual & auto will make a difference.

 

with 4th gen v8 cars, ALL manuals have 3.42's, autos with the GU2 code on the door have 2.73's, and autos with the GU5 code(performance rear) have 3.23's

 

Is the 3.42 a GU6

 

Yes GU6 is 3.42

 

AFAIK, all the SS's and WS6's should have come with the "performance" rear axle, which was 3.23's (AND the aluminum driveshaft). As mentioned, ALL 6-speeds came with 3.42's (except '93, where they actually came with 3.23's as well, right??) and the 6-speeds had aluminum DS as well.

But as far as A4's w/2.73's, that's the "standard" ratio for A4's, with a steel driveshaft, but any Z28 / Trans-Am could be ordered with the 3.23's as an option, so it's hard to know for sure how many had what. Chances are the majority of "base" V8's got the 2.73's.