Gear codes

[bowtiefreak]

It has come up more and more. Everyone should know whats in the truck. Below are the stock gear codes found in the glove box. You will have one and possibly two of the following codes if you have the G80 option. I have also listed a helpful gear to tire size chart to help people better understand.

GT4 -- AXLE REAR, 3.73 RATIO
GT5 -- AXLE REAR, 4.10 RATIO
GU4 -- AXLE REAR, 3.08 RATIO
GU5 -- AXLE REAR, 3.23 RATIO
GU6 -- AXLE REAR, 3.42 RATIO
G80 -- AXLE REAR, locking differential (has many names, none being good but that brings up a whole other discussion)

 

[BluHoe96]

Wow! Big help on this glad u posted it. Looking for a rim and tire setup now so this is a big help!

 

[97.twodoor.4x4]

Bowtiefreak. I was wondering if I run a 3" body lift along with a 3" suspension and run 35 or 36 tires am I gonna run into trouble not regearing my truck?

 

[raptorforme93]

I was perfectly fine not knowing that I have the G80!!! But I do Im about %90 sure that it doesnt work, but I havent tested it out. And I have a 3.42 ratio which also isnt fun. Thanks for the info though! I would never have known otherwise

 

[Bad bow tie]

Bowtiefreak. I was wondering if I run a 3" body lift along with a 3" suspension and run 35 or 36 tires am I gonna run into trouble not regearing my truck?

35" you should have at least 4.56 gears. Anything bigger should be 4.88 or even 5.13. You could probably get by on 4.10s for 35's but you will run the risk of putting extra strain on your engine and tranny.

 

[ELOOSECANNON]

How can you tell which code you have? I looked at the sticker in the glove box and there's like 6 or 8 columns of codes. Which ones are for what? I'm confused.

 

[Bad bow tie]

The codes are given in a number/letter ratio. For example: GT4 stands for a trucks gear ratio.. this specific code means the truck has 3.73 gears. Yours may be different. These codes give every option your truck came with from the factory. I.E. trim level, packages, everything from leather interior to sterio system to mechanics like tranny type, gear ratios, and engine types. It tells you everything and is pretty much a build sheet for your vehicle.

The best thing to do is to take a picture of your label located in the glove box and look them here http://www.rpocodes.com/

Hope this helps.

 

[SunlitComet]

Or enter your Vin here:

http://www.compnine.com/vid.php

 

[99Yuk]

...The best thing to do is to take a picture of your label located in the glove box and look them here http://www.rpocodes.com/...

...hehehe. I couldn't remember all those codes either, so I took a pic too....

 

[coleman84]

Very helpful, thanks for posting!

 

[chitown906]

I too have the 3.42 with locking rear.. interesting

Chi_Town

 

[SunlitComet]

That locker will blow sooner than later if you stress it a lot. Will be waiting for pictures when it does.

 

[Dazrin]

So, I have stock 3.73 gears and 265/75R16 tires. If I go 315/75R16 tires, it looks like I should be OK with 4.10 gears. I see most people recommend 4.56 though. Is that just for the power? What is the trade-off? 1-2 MPG?

I ask because I can get a 14 bolt rear axle with 4.10s for $150 which will end up being cheaper than putting 4.56 (or 4.10) in my current 10 bolt plus I get a 14 bolt.

It doesn't seem like it would be sacrificing much to do that, but wanted to check what other people thought about this.

 

[bowtiefreak]

you could run on 4.10, but many people like the 4.56 or even 4.88. I run a 315/70/17 and wish I would have done a 4.88 sometimes

 

[LOU A VILLE]

Sorry for bumping this old thread but its stickied so it shouldnt matter to much.

Just looked and my sticker says Gu6 and then G80 right after, How bad is the G80? Im clueless. I will be getting new tires 265/75/16, is 3:42 gearing going to be betteror worse for gas then another? sorry for all the questions, just trying to learn.

 

[bowtiefreak]

for those tires, your gears are fine. You will never see a difference. The G80 can be the start to a bad day....

Do you ofroad the truck or beat the piss out of it on the road? If yes, your days are numbered.

Typically I hear guys toasting them when spinning the tires then catching and BOOM.

I ran one for 8 years with no problem, ignorance was bliss and I had no idea what was in there. I swapped it when I regeared. But many run them for a long time. Others, kill one a year or more.

 

[andrewlee]

I have g80.. & 3.73 should I be ok 33'' tire?

Sent from my LS670 using Tapatalk 2

 

[Donnie Yukonie]

great info , always been told at the dealership mine was the 3.73 not according to my sticker says i have the 3.42 g80

 

[bowtiefreak]

3.42 is a very common ratio. It seems if the truck came with a towing package you will see 3.73 or even 4.10 though.

Andrew: you should be fine with a 3.73 and 33. It's not worth changing to be honest.

 

[Donnie Yukonie]

well thats just it i have the towing package truck came with a class 3 hitch and "heady duty trans something according to my RPO codes guess thats why I and the dealership always assumed it was a 3.73
Z82
VR4
KNP
are all codes i have but appearently i have the smaller ratio? kinda seems a bit odd to me