How to identify rear diff gear ratio.

[ROGELIO A GUZMAN]

Hey fellas . Is there a way to identify the rear diff gear ratio. I don't have much paperwork on the xl, Im just curious to see and also the transmission. What do I have. I'm awd so im not sure. 4l60 or 4l65e

 

[mpope2]

Can you post of picture of the RPO code sticker in your glove box? It has a series of alphanumeric sets that identify various options on your vehicle. Some of the more common ones you will see are GU6, GT4, GT5, etc

 

[wjburken]

Hey fellas . Is there a way to identify the rear diff gear ratio. I don't have much paperwork on the xl, Im just curious to see and also the transmission. What do I have. I'm awd so im not sure. 4l60 or 4l65e

I’m pretty sure your vehicle has a 3.73 axle, but as was already mentioned, a look at your RPO sticker in the glove box will help confirm.

 

[S33k3r]

Put it up on a jack stand, with the rear wheels FULLY off the ground. Make sure it is in Neutral. Then rotate the tires and watch the drive shaft. So this is the part I keep messing up, so double check me... If the wheels don't quite rotate 4 times when the driveshaft rotates one, then you likely have 3.73 gears. If the wheels rotate more than 4 times for one of the drive shaft, then you have 4.10s... The part I confuse is which is supposed to rotate more -- the driveshaft or the wheels, but this gives you an idea on how to do it -- if you don't have RPO codes. If you have RPO codes, GT4 is 3.73 gears, and GT5 is 4.10 gears.

 

[ROGELIO A GUZMAN]

Can you post of picture of the RPO code sticker in your glove box? It has a series of alphanumeric sets that identify various options on your vehicle. Some of the more common ones you will see are GU6, GT4, GT5, etc

Thank you I will when I get home.

 

[wjburken]

Put it up on a jack stand, with the rear wheels FULLY off the ground. Make sure it is in Neutral. Then rotate the tires and watch the drive shaft. So this is the part I keep messing up, so double check me... If the wheels don't quite rotate 4 times when the driveshaft rotates one, then you likely have 3.73 gears. If the wheels rotate more than 4 times for one of the drive shaft, then you have 4.10s... The part I confuse is which is supposed to rotate more -- the driveshaft or the wheels, but this gives you an idea on how to do it -- if you don't have RPO codes. If you have RPO codes, GT4 is 3.73 gears, and GT5 is 4.10 gears.

He will need to get all 4 wheels off the ground to do what you are saying as his vehicle has AWD.

 

[S33k3r]

He will need to get all 4 wheels off the ground to do what you are saying as his vehicle has AWD.

<Sigh>. We had to do that with my daughter's Sierra Denali; the original differential we were shipped from Summit was 3.73, even though 4.10 was purchased and the case was identified as 4.10. Sorry about forgetting that.

 

[swathdiver]

Hey fellas . Is there a way to identify the rear diff gear ratio. I don't have much paperwork on the xl, Im just curious to see and also the transmission. What do I have. I'm awd so im not sure. 4l60 or 4l65e

Those Denalis only had one gear option, 3.73s.

 

[bigdog9191999]

i know our denali is 3.73 as is the escalade I am snagging for parts.

 

[ROGELIO A GUZMAN]

Those Denalis only had one gear option, 3.73s.

Ok thank you.