# how to tell what axle ratio w/o pulling cover?

Discussion in 'The Garage' started by Cornfield creations, May 19, 2006.

1. ### Cornfield creations1/2 ton status

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Need to know how to find out the axle ratio on a 72 k-5 without pulling the diff. cover.

Dealership said that it's stamped on the axle tube, between the spring and tire on the driver rear axle. I cleaned it off and didn't find anything.

any help in appreciated

2. ### resurrected_jimmy1/2 ton status

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put a chalk mark on the driveshaft and one on the tire, jack the rear end up and turn the tire by hand 1 rotation while counting the number of turns the drive shaft makes. A little over 3 turns on the driveshaft = 3.08's, 3 3/4 turns of the driveshaft = 3.73's, and so on

3. ### theperfectgarage1/2 ton status

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Put a line on the drive shaft, a line on a tire, jack it up and turn the driveshaft by hand while counting the number of rotations ( including the fraction ) of the d-shaft to get one complete tire rotation. That should get you close enough. Ex; 3 and 3/4 turns on the d-shaft = 3.73 ratio.

4. ### theperfectgarage1/2 ton status

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wow, I hit enter and saw your post... your a smart guy. edit- takes me 15 min. for a quick post 'cause I'm at work.

5. ### sandracer7991/2 ton status

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Look up the RPO code in the glovebox.

6. ### pvfjr1/2 ton status

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I think you guys are sending him in the wrong direction.

Assuming you have a open diff....
You need to turn BOTH tires perfectly once, or ONE tire TWICE. Because of the operation of the spiders, you can turn one tire in two complete circles. This is the same as turning both tires in one complete circle, but a little easier to manage and a lot more accurate. So just jack up one tire, put a mark on it and the driveshaft, and turn the tire around twice and count the number of times that the driveshaft spins.

7. ### theperfectgarage1/2 ton status

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Whats an open diff? .... Very good point.

8. ### atho1/2 ton status

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i 2nd the rpo sheet. if no gear ratio listed, what is the engine? if there is no engine indicated, does the VIN denote L6 or V8?

my guess is 3.07, originally with a 350.

9. ### Cornfield creations1/2 ton status

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yeah i tried the vin code and the glove box, couldn't find anything. yeah it has a 350/350TH. I am hoping for 3:73, but I don't wanna waste my time getting the thing running so I can get it out so I can check the gears by pulling the cover.

10. ### broncoman65241/2 ton status

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I've gotta question bout the raisin up one side of the axle. Do you have to have the tire on to do it? Like say i was in a junkyard i dont wanna pull a buncha diff covers trying to find the right gears.

11. ### MattK1/2 ton status

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if the axle shaft is there to turn that will work as well. otherwise you'll be countin teeth.

12. ### broncoman65241/2 ton status

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alright i tried this on my truck today and i dont know WTF i did but it didnt work. I jacked up the Right rear tire put the T-case in neutral and tried to spin the tire. It was still locked into the Front driveshaft. I fired up the truck and played with the gear selector thingy until the truck wouldnt move on its own power. Still wouldn't let me turn the tire. I also tried it with the tranny and the T-case in neutral and it still wouldn't let me spin the tire.

Is there something wrong with my T-case or could my hubs be stuck in the "Lock" position? (i have auto hubs)

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