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.

 

[wjburken]

I dont believe that sheet is in my glove box.

Where else can i look to find this?

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It looks like this:

 

[swathdiver]

I dont believe that sheet is in my glove box.

Where else can i look to find this?

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If missing you can send an email to GM with your VIN and they will send a reply with all of the codes and what they mean. Conversely, there's a company that let's you get 5 VIN checks for $5 but the name escapes me at the moment. Fellas, do you remember the one?

 

[Bob2C]

My 02 Yukon had 4.10 rear. Took off fast. 17 years later my brother still has the truck. Needs a paint job but mechanically sound.


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[Woodblocker55]

I have a 5.3 L 4:10 it's a stop light launcher . You need to becareful with G80 posi . The rear will brake loose pretty easy ya both wheels and slide to the side at launch . And yes rigs with 4:10 seem to last longer this reason I think it 200 rpm more keep the bands tight in tranny that's my opinion . But on other hand 4:10 people do abusing them more.
Because I drove mine about 5000 miles I will always want 4:10 gears . Now next crop after 2006 they have more gears that adds more stuff going on . More gears In tranny will compensate for Towing so you don't need the low gear rear end tranny does it for ya . Well see how that holds up .
More stress in tranny isnt really ideal to me but I'm old school I can only guess tranny's run hotter .
And tranny's are week point anyway . But thats the GTM900 guys can address [emoji106]

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[swathdiver]

I have a 5.3 L 4:10 it's a stop light launcher . You need to becareful with G80 posi . The rear will brake loose pretty easy ya both wheels and slide to the side at launch . And yes rigs with 4:10 seem to last longer this reason I think it 200 rpm more keep the bands tight in tranny that's my opinion . But on other hand 4:10 people do abusing them more.
Because I drove mine about 5000 miles I will always want 4:10 gears . Now next crop after 2006 they have more gears that adds more stuff going on . More gears In tranny will compensate for Towing so you don't need the low gear rear end tranny does it for ya . Well see how that holds up .
More stress in tranny isnt really ideal to me but I'm old school I can only guess tranny's run hotter .
And tranny's are week point anyway . But thats the GTM900 guys can address [emoji106]

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That's right Joe, good combination. Of course in 3rd gear a GMT800 with the 4-speed and 4.10s has a final drive of 4.10:1 and running a 265-70-17 tire would be turning 2600 rpms @ 60 mph.

4th gear in a GMT900 with the 6-speed and 3.42 gears is a 3.94:1 final drive running the same tire is turning 2500 rpms @ 60 mph.

4th gear in a GMT900 with the 6-speed and 3.73 gears is a 4.30:1 final drive running the same tire is turning 2750 rpms @ 60 mph.