Rear end gear ratio change

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STREETutilityVEHICLE

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I am wanting to go with a lower gear, but don't really know what I have so I don't know how low I want to go. I have a 2003 LS Tahoe 4.8L can anyone tell me what gear ratio i am running by that info? And as far as changing them, when I look in Jegs or Summit, what ring am i looking for? How many bolt, how big, etc? I don't really want to order the wrong set of gears, ya know? THANKS!
 

JKmotorsports

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Look at your RPO label which should be in the glovebox.
GT4 denotes 3.73 ratio
GT5 - 4.10
GU6 - 3.42

I believe we are running 8.5" ring gear if I'm not mistaken. If you type in your vehicle make and model on the Summet site, it should pull up only the parts that will fit your model and trim vehicle.
 

dye4metal

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also for buying gears you can go onto 4wheelparts.com its really easy on their site.
 

boostaholic

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What size tire and how much do you care about mileage? I'd run 4.30s or 4.56s with 285s, 4.10s with 265s.
 

STREETutilityVEHICLE

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i'm running 265's at the moment. but i was swapping out for 305/40/22 in a few weeks. but it's looking like i will be going w/ a 305/35/23 or 305/35/24. Anyone running 23 or 24's with 4.56's or 4.10's? What are your highway RPM's like? Like 75-80ish @ ? That's my main concern, I hit the highway from time to time, but mostly in town driving. I don't want to be running 4,000rpm @ 70mph roaring off a set of super 44 flows and 24's, ya know. Especially when riding dirty. But on the other hand, i am going with a lower gear, it's just what ratio, so anyone with gears please chime in and let me know what kind of rpms your pushing @ different speeds if you will. thanks!
 

STREETutilityVEHICLE

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I looked in the glove box and i saw the GU6 code. I guess I'm running 3.42's and i'll be going with 3.73's or maybe 3.90's. Thanks for the help everyone! Let me know if ya'll see a good price on some gears, thanks
 

STREETutilityVEHICLE

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I can't find the gears i need, anyone know where they sell, either 3.73's or 3.90's for our trucks? I know it's an 8.5" ring gear, but don't know anything else about it. Anyone know a part number to Jegs or Summit or anyone else? thanks
 

boostaholic

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8.6" ring gear uses a specific install kit but any of the 8.5 10 bolt gears will work. What brand do you want? I can get you part #s from genuine g2s, precision, yukon, dana spicer, etc. They sell both 3.73s and 3.90s but I'd go 4.10s if you're running a 30"+ tall tire.
 

STREETutilityVEHICLE

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I'm just slightly worried about going 4.10+ on my gears b/c i hit the highway sometimes and don't want to murder my highway RPM's. Anyone on 24's with 4.10 gears? I'm just trying to find what kind of RPM's people are turning w/ lower gears on the highway. I may go with a 4.10 but I'd have to know what it's turning at 70MPH. Ya know? Doesn't Richmond make a good gear kit? Any kit that's of good quality and has all the parts needed for the swap will work. Thanks for the help boost!
 

alex29573

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any more info on this???

im running 305/45/22 and was wondering how the 4.10s would be on the highway....

does anyone know the gear ratios in the tranny...
Im asking because there are websites that calculate what each gear will top out in mph according to your tire size/tranny ratios/differential ratio...
 
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