What differential type is in my '01 Yukon XL 5.3?

Hello, I was wondering if anyone possibly knew what type of diff my Yukon has. It is a 01 Yukon XL 5.3L 1500 automatic. I would like to know the size... I read that they made 3 different sizes for the the Yukon XL. And also diff type (open, locking, or limited.) Please. Thank you!

Find your RPO code label and look for codes such as GT4 (3.73), GT5 (4.10), GU4 (3.08), GU5 (3.23) or GU6 (3.42). If you see "G80", then you have the OEM limited slip (Gov-Lock) differential. I don't know if there's a specific RPO code for the open diff. Also, I don't know exactly where the label would be on your Yukon. Early 2000s and older, they were in the glovebox, usually on the backside of the door. It may be on the passenger doorjamb. It's a white sticker, about 3"x2" with a bunch of 3-digit codes on it. It'll have your paint code on it as well, if that's useful to you. If you don't have the RPO sticker, you can stop by a GM dealer and give them your VIN and they can print up a build sheet for you. If they tell you they can't, find another person or dealership that knows what they're doing.

You've got the smallest one. The 2500s had the larger GM or Dana 60 (Quadrasteer) axles. But a quick look at Rock Auto showed 4!

Plug your vin into GMPartsdirect.com and it will tell you what you have.

I figure you'll have a GM 10-Bolt 8-5/8" Rear.

Dub, The ring gear codes will not specify the differential type. A long time ago G87 meant an 8-1/2" rear and G89 meant a 7-1/2" rear, this was for the G-Bodies, cars like the Olds Cutlass and Buick Regal and Monte Carlo.

My RPO sheet has just 2 "G" codes, for the Posi/Locker and for the Ring/Pinion Gear Ratio. But like yours, mine is a GMT900. Not sure for the older ones.

swathdiver said:

Dub, The ring gear codes will not specify the differential type. A long time ago G87 meant an 8-1/2" rear and G89 meant a 7-1/2" rear, this was for the G-Bodies, cars like the Olds Cutlass and Buick Regal and Monte Carlo.

My RPO sheet has just 2 "G" codes, for the Posi/Locker and for the Ring/Pinion Gear Ratio. But like yours, mine is a GMT900. Not sure for the older ones.

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Right- Gear ratio and differential type are two different things and are represented by two different RPO codes. I listed the ratio codes I knew as well as the one differential code I knew (G80) since the OP wanted to know the size and diff type. I didn't mean it to sound like I meant "G80" was a diff and ratio type all in one. Also, technically speaking, the Eaton Gov-Lock isn't so much of a "limited slip" differential as it is a "locking" differential. "LSD" is somewhat accurate and shorter to type for us lazy people. I guess I could say by LSD, I mean "limited SPIN differential"?

AFAIK, GM has been using the same Gxx RPOs since at least the mid- to early-90s. A GU6/G80 in a '95 F-body 7.5" 10-bolt referred to the 3:42 ratio with the LSD just as it does in a 2009 Tahoe with an 8.5" 10-bolt.

swathdiver said:

Plug your vin into GMPartsdirect.com and it will tell you what you have.

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I didn't know there was an online VIN decoder that would return this info. That's much better than having to go to a dealer.

Well, it's not a VIN decoder but there software will populate the parts for his vehicle based on the VIN entered. I use it all the time and often purchase from them too, top notch folks. I've dealt directly with one of their service departments in North Carolina.

The GU6/G80 goes back to at least 1984 with the Buick Grand National. My memory isn't what it once was but I think these codes were even used on the Skylarks back in the late 1960s and early 1970s as well. I think it was before '84 or so you had to find the build sheet as we didn't have an RPO sticker. We often found them under the seats between the wire and cushion.

iamdub said:

Find your RPO code label and look for codes such as GT4 (3.73), GT5 (4.10), GU4 (3.08), GU5 (3.23) or GU6 (3.42). If you see "G80", then you have the OEM limited slip (Gov-Lock) differential. I don't know if there's a specific RPO code for the open diff. Also, I don't know exactly where the label would be on your Yukon. Early 2000s and older, they were in the glovebox, usually on the backside of the door. It may be on the passenger doorjamb. It's a white sticker, about 3"x2" with a bunch of 3-digit codes on it. It'll have your paint code on it as well, if that's useful to you. If you don't have the RPO sticker, you can stop by a GM dealer and give them your VIN and they can print up a build sheet for you. If they tell you they can't, find another person or dealership that knows what they're doing.

Click to expand...

iamdub said:

Find your RPO code label and look for codes such as GT4 (3.73), GT5 (4.10), GU4 (3.08), GU5 (3.23) or GU6 (3.42). If you see "G80", then you have the OEM limited slip (Gov-Lock) differential. I don't know if there's a specific RPO code for the open diff. Also, I don't know exactly where the label would be on your Yukon. Early 2000s and older, they were in the glovebox, usually on the backside of the door. It may be on the passenger doorjamb. It's a white sticker, about 3"x2" with a bunch of 3-digit codes on it. It'll have your paint code on it as well, if that's useful to you. If you don't have the RPO sticker, you can stop by a GM dealer and give them your VIN and they can print up a build sheet for you. If they tell you they can't, find another person or dealership that knows what they're doing.

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So on my sticker i found both GT4 and G80... is this the sticker im suppose to look at?

That's the one! Now as for the size, how many bolts are on the rear cover? Why don't you decode your VIN over at compnine for $5?

yukonxlfan said:

So on my sticker i found both GT4 and G80... is this the sticker im suppose to look at?

View attachment 183891

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Yup. That's it. GT4 is the 3.73, G80 means you have the Eaton locker.

HiHoeSilver said:

Yup. That's it. GT4 is the 3.73, G80 means you have the Eaton locker.

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Indeed, I have the same rpo's so this is accurate or was accurate in my case... now I'm rollin 5.13's. Those 3.73's I had were SCREAMING for help once I jumped to 37/13.50's lol!