Are there different rear diff or transmission gear ratios with different model years?

[UmmScott]

Just like the title says.

Reason for asking, comparing my 00 nbs yukon to my Moms 2003 suburban LT.
Both 4wd with the 5.3 and 4L60e.

My moms will take OFF from a stop and throw you in the seat LOL
Mine...is kinda lazy at the first punch but... mine seems to get way better gas mileage and i dont seem to have to lay into it on the highway as much.

So are there different gear ratios OR is it purely in tuning?

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[Chris2144]

4l60e in the those have the same ratios. As far as rear axle there are different ratios. The two most common are 342 and 373. Usually anything with the towing package got the 373. This can be checked by the rpo code in the glove box. I forget what it is for those gt5 and gu4 I think but I'm sure one of the other guys here know those codes. Also tire and wheel size can have a big impact here because it essentially changes final gear ratio

 

[HiHoeSilver]

GT4 = 3.73
GU6 = 3.42

 

[kybob]

What Chris said. ++
Also, I’m betting yours is running lower RPM’s at highway speeds vs your Moms.
I knew nothing of the RPO codes, but thanks to this forum, I was able to look them up. ( much thanks to the helpful folks on here )


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[SUBURBIAN]

Just like the title says.

Reason for asking, comparing my 00 nbs yukon to my Moms 2003 suburban LT.
Both 4wd with the 5.3 and 4L60e.

My moms will take OFF from a stop and throw you in the seat LOL
Mine...is kinda lazy at the first punch but... mine seems to get way better gas mileage and i dont seem to have to lay into it on the highway as much.

So are there different gear ratios OR is it purely in tuning?

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Same ratios year to year:

3.08
3.42
3.73
4.10

They're just different truck to truck. My '05 is 3.42, and my '03 is 3.73.

 

[OR VietVet]

I was gonna guess a 3.73 gear for the Suburban but if it is the 3/4 model could be the 4.10 gear depending on the package.

 

[swathdiver]

As mentioned earlier, check the RPO sheet in each glovebox and see what they have.

 

[UmmScott]

Thanks a bunch guys.
Im gonna check and report back what i have

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[UmmScott]

I dont believe that sheet is in my glove box.

Where else can i look to find this?

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[OR VietVet]

It will be attached at the glove box door on the inside. I have even seen them at the glove box floor area where you have to remove all that is in the glove box to see the sheet. It will not be a loose piece of paper.