Axle Ratio
Junior User
Joined: Feb 2010
Posts: 85
Likes: 0
Mine wasn't actually on the door, the build tag was installed on the body of the truck. If you open the drivers door, look down in the space between the drivers side front and drivers side rear door. That's where my build tag was installed.
Cargo Master
Joined: Mar 2005
Posts: 2,790
Likes: 24
From: Mount Royal, NJ
Well, at least you can tell something.
Jack up only one tire in the rear. Leave the other on the ground. If the one tire in the air will not spin (with parking brake OFF, trans in neutral), then you probably have some sort of limited slip or locker. If it does spin, you probably have a open differential.
If it is a open differential, mark the driveshaft (chalk) so you can see how many rotations it takes. Rotate the tire exactly TWO revolutions and count the turns of the driveshaft. The number of turns of the driveshaft is your axle ratio. It could be: 3.73, 4.10, 4.30, or 4.56.
If it is a limited slip, then jack both tires into the air and mark the driveshaft as before. rotate the tire exaclty ONE turn and count the driveshaft rotations. The number of turns is your axle ratio.
If you have a limited slip of some kind, the only way to identify it will be to remove the cover and look at it to see what type and make it is.
Jack up only one tire in the rear. Leave the other on the ground. If the one tire in the air will not spin (with parking brake OFF, trans in neutral), then you probably have some sort of limited slip or locker. If it does spin, you probably have a open differential.
If it is a open differential, mark the driveshaft (chalk) so you can see how many rotations it takes. Rotate the tire exactly TWO revolutions and count the turns of the driveshaft. The number of turns of the driveshaft is your axle ratio. It could be: 3.73, 4.10, 4.30, or 4.56.
If it is a limited slip, then jack both tires into the air and mark the driveshaft as before. rotate the tire exaclty ONE turn and count the driveshaft rotations. The number of turns is your axle ratio.
If you have a limited slip of some kind, the only way to identify it will be to remove the cover and look at it to see what type and make it is.
Cargo Master
Joined: Mar 2005
Posts: 2,790
Likes: 24
From: Mount Royal, NJ
Do you have a metal tag on the diff cover? We can decode that.
IF all else fails, you can get the BOM (Bill Of Materials) number off of the FRONT axle tube and we can decode that to give you your axle ratio.
IF all else fails, you can get the BOM (Bill Of Materials) number off of the FRONT axle tube and we can decode that to give you your axle ratio.
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Senior User
Joined: Feb 2010
Posts: 117
Likes: 0
From: Castle Rock, CO
It sounds like alot of work... Maybe I dont really need to know that bad....lol. Judging by the RPMS, I am assuming they are 3:73s... Hard to know with the bigger tires and all though.
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