finding gear ratio in '05 GMC Sierra

kilby

kilby

Member
Joined
Mar 17, 2005
Location
Charlotte, NC
Sure. This is a noob question. But here you go...

Let's say there's no tag on the rear axle (because there isn't one).

Then what's another way to determine what gear ratio is in the rear end in a 2005 GMC Sierra, crew cab, 2WD. Please note: I don't want to crack the diff and count teeth, and I'm not sure I could tell the difference by turning the shaft and counting wheel rotations. I know it's either 3.73 or 3.23.

There's gotta be a VIN code or sticker I can look for, right?
 
Look in the glove compartment, There will be a list of 3 digit RPO codes that will list every option your truck has. You can google GM RPO Codes, and find a PDF format list of each code, so you can find every option you have.

But for your specific question,
GQ1 -- AXLE REAR, STD RATIO
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, LIMITED SLIP (AKA the Eaton Gov-Bomb locker)
HC4 -- AXLE REAR, 4.56 RATIO-Military option
 
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