intmd8r

Hey there! I am trying to dechiper my RPO codes and I have found myself unable to determine what axle I have!

I am looking at the RPO codes for my '04 from here: http://www.corvetteactioncenter.com/.../2004prod.html

I have the following codes regarding my axle:

GU2: (Std Axle Ratio 2.73:1 MX0 Auto)
M30: Elect. 4spd. Automatic Transmission
MX0: M30 Elect. 4spd. Automatic Transmission (Includes G92 Performance Axle Ratio)

G92 is listed twice at that site as:

G92: Perf. Axle Ratio - 3.15:1 MX0 Auto (Not Avail w/Z06)
and
G92: Rear Axle Ratio - Performance

Now, I do not have G92 in my glove box, but MX0 implies that I do.

So, short of crawling under the car, do I have 2.73 gears or 3.15 gears?

blacksedan87

Take the car out on the 101 - take it up to 75mph in 3rd (not 4th - that's overdrive) and look at your tach. If you are running at 2730 rpms - then you have a 2.73 and conversely if you are running at 3150, you have a 3.15, etc. 3rd gear is the gear in an A4 that is 1:1.

This technique also works for the MN6 - except you do it in 4th gear instead of 3rd, again 4th is 1:1 in the MN6.

Here's a little better explanation of the RPO codes....

http://home.fuse.net/corvette/rpo.htm

screw991le

Look for G90 and GU2

If your RPO sticker says G90 then you have 3:15s
If your RPO sticker says GU2 then you have 2:73s

Ignore the other codes, which do you have?

GrayC5

Also, the following web site has one of the most comprehensive lists of C5 RPO codes that I've found:

C5 RPO Codes

HTH

intmd8r

Awesome, thank you, I will do just that.

I have always thought I had 2.73s because I have GU2. Then today I noticed the MX0 thing that says (includes G92) which is 3.15s, and my mind just went !

I'll take her out on the 101, though, and see what we come up with at 75 mph.

Thanks!

eddie44

I've got 3:15's so you could tell real quick if we just race (oh wait, we can't say that here)

intmd8r

We could have done that today! (Oh wait, probably can't say that either! )

At any rate, from what was posted above (http://home.fuse.net/corvette/rpo.htm), I do indeed have 2.73s, but I also have Rear Axle Ratio - Performance.

Ok, so what is that?

Z-07 freak

No, you don't (have the performance axle).

The word "included" from the Corvette Action Center site, simply means the MX0 M30 Elect. 4spd. Automatic Transmission uses the base (GU2) 2.73 ratio or the optional (G90) 3.15 ratio.

It is trying to state that the (GU6) 3.42 ratio is not available with an automatic.

eddie44

GM marketing???

intmd8r

Ok, so I'm guessing I likely just have the 2.73s, which brings me full circle to what I've always thought!

screw991le

If you have GU2s then you have 2:73s. But look on the bright side, you'll get better gas mileage.