[jgard07]

Does anyone know what rear gear my 07 GT has? The axle code is "CD". I bought the car used so I didn't get a window sticker. Thanks in advance for any help.

[jre8806]

3.31's if its auto, 3.55's if its manual transmission

[jgard07]

Thanks for the info jre. It is a manual. Runs about 2200 rpm at 70 mph in 5th gear.

[DGS]

I have a 07 GT 5-speed with 3.31's......don't know how that happened?
My gear housing cover says 3.31 on it and my axle code is CG.

How are the 3.73's? I may go to that since I do a lot of highway driving.

[stlwagon]

3.31s are stock on both auto and manual for 2007. 3.55s are optional on the manual.

[cerino2000]

there is a sticker on the rear end housing that you can easily see from the back of the car when underneath it that will tell you your gear ratio.

3.55 is in fact a $100 option.

[stlwagon]

Originally Posted by cerino2000

there is a sticker on the rear end housing that you can easily see from the back of the car when underneath it that will tell you your gear ratio.

3.55 is in fact a $100 option.

And certainly worth the $100 unless you plan on changing to another ratio anyway.

[cerino2000]

I agree, $100 well spent.

[jre8806]

the 3.73's are fantastic, I can feel it take off, not as much as 4.10's, and I still get my Top End speed.

[MakeMyStang]

Originally Posted by stlwagon

3.31s are stock on both auto and manual for 2007. 3.55s are optional on the manual.

Yes that is correct. Auto for 07 only came with 3.31 and manuals came with 3.31 but for 100.00 they offered the 3.55 manuals only, which i put into the car when ordered built.

In 06 they were optional at no cost for the 3.55 with man. tranny

[sqidd]

Originally Posted by DGS

I have a 07 GT 5-speed with 3.31's......don't know how that happened?
.

Me too.....................

[DGS]

Lucky me with the 3.31's!
With highway driving sounds like the 3.73's or 3.90's would be a HUGE improvement.
Without a big increase in RPM.
I drive the 101 everyday and normally cruise around 80....that's right.
Let me know what you guys think.

[travelers]

CD means you have 3.55 gears. It's what I have and I ordered mine with 3.55.

[sedg49]

Posted for the person that wanted to go to a 3.73:1 axle and does a lot of highway driving. The higher the axle ratio number, the lower the car's top end. It will also turn a higher RPM for a given speed compared to a numerically lower rear end and use more fuel. The numerically lower rear end will allow the car to have a higher top end and burn less fuel at a given speed when compared to a low speed (high numeric) rear end. That is why a dragster has a 4.11:1 or numerically higher rear end ratio so the torque is there and the top end is achieved a lot quicker. I apologize if this is boring to those that are in the know. So if you want MPGs and a lower RPM while motoring in your '07 Mustang, stay with a 3.31:1 axle. Happy Cruising.