I just bought a used 2002 Z28 Convertible with an auto. How can I tell which gears it came with? If it's any help at 70 MPH the tach is at 1700 RPM.

 

Looks like 2.73's according to that MPH/RPM. Check the RPO codes on the driver's door

GU2 = 2.73
GU5 = 3.23

 

You got 2.73's. I am at 2100 rpm's at 70 mph with my 3.23's.

 

I thought if you have 2.73 gears, then in 3rd gear (for an auto) or fourth gear (manual) at 70 MPH your RPMs should be at 2700, 3200 for 3.23, 3400 for 3.46 etc....

 

Here's another way to check depending on what gear your in/or if you suspect they may have been changed: www.f-body.org/gears/

 

That could be but no one with an A4 drives in third on the highway unless they like wasting gas. Generally people say with an A4 it's best to drive around the city in third and shift to overdrive at any time they are going to go 45 mph or better for any extended length of time.

So the above rpm's of 1700 and 2100 (for me) were in fourth gear, not third.

 

Exactly the 70MPH test only works when an A4 is in third. I used to turn around 2700 when I had my 2.73's. God I'd hate to imagine how many RPM's I'd be turning at that speed in third now.