Help! What ratio are my k10 axles?

[AlexK10]

Hi everyone, I have a 1984 K10 with a 305 and 700r4, which needs a new rear gear/pinion set because of wear slop back there. Last time I had the covers off I didn't count the teeth so I tried to figure out the axle ratio by doing the following:

Rear open diff.
Lifted one side only, trans in neutral, ebrake off, marked the rear yoke and the tire in reference to the wheel well.
Spun the tire two revolutions while looking at the yoke. The yoke spun less than 3 1/4 turns, which makes it a 3.07 or 3.08 is my guess. Then again I don't know if these trucks came with, or chevy made both 3.07 and 3.08s for the 10bolt.

Which one is it?

For the front axle...
I did the same procedure with the manual hub locks engaged in the "lock"position.
The axle didn't complete 3 turns with 2 turns of the wheel.
Whats going on with the front?

Confusing Update: I just saw online charts showing my engine to trans and year to have 3.23, 3.73 in one chart and 3.06:1 in another.

3.06, 3.07, 3.08, 3.23, 3.73 or anything between?

 

[AlexK10]

I found this online: https://www.tfloffroad.com/2019/04/...ay-to-find-the-rear-axle-ratio-on-your-truck/

It seems that another/maybe correct method would be to spin the tire 10 times not two and then multiply the drive shaft rotations x2 and move the decimal over.

quote from website noted above:
"In our case, we counted 18.75 spins of the drive shaft, which when doubled is 37.50. Then, because you spin the tire 10 times, you move the decimal point over one, ending with 3.75. Now, in our case, I know that Chevy doesn’t offer a 3.75, but does offer a 3.73, so by simple deduction, I found out that my truck has a 3.73 in the rear."

Should I do this procedure or something else?

 

[Turbo4whl]

Still have the RPO code list in the glove box?

RPO AXLE CODES:

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 (POSITRACTION)

Should I do this procedure or something else?

Count the teeth, you'll know for sure. Spinning the wheel should get you close, but some ratios are also close to each other and maybe you will not get the correct gear set.

 

[DoubleDingo]

Yep, pop the cover, count the teeth.

 

[AlexK10]

I would prefer to remove the cover when Im ready with all the parts in hand to replace them, If possible avoid removing the cover, gear oil, rtv twice is what I mean.

Whats left of the label where the RPO code is:

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GQ1 which means "standard ratio". That does not say much about the actual ratio.

 

[DoubleDingo]

Or if the gears were changed at some point. You'd know by now if you just popped the cover.

 

[AlexK10]

What other parts I would need to order while I'm replacing the ring and pinion?

Like seals, bearings and bearing races, or related parts accessible while I'm in there.

 

[Rusty Nail]

3.08

 

[SquareRoot]

Pop the cover. Don't be lazy. Or, be lazy and let everyone speculate. A tube of silicone is like $7. If you're cheap, reuse the oil. Don't be lazy.

 

[Turbo4whl]

What other parts I would need to order while I'm replacing the ring and pinion?

Like seals, bearings and bearing races, or related parts accessible while I'm in there.

Yes, all those parts, new ring gear bolts too. Have you ever built/ setup a rear axle? There is a trick to it.

 

[Turbo4whl]

Pop the cover. Don't be lazy. Or, be lazy and let everyone speculate. A tube of silicone is like $7. If you're cheap, reuse the oil. Don't be lazy.

"....If your cheap, reuse the oil."

"Now that's funny, I don't care who you are." -Larry the Cable Guy

 

[Rusty Nail]

Mebbe 2.76? was the default making 3.08 an option.
I wanna change my answer to 2.76.

 

[Turbo4whl]

Mebbe 2.76? was the default making 3.08 an option.
I wanna change my answer to 2.76.

Default gear could be that 2.76 with a 3 speed. I hope we convinced the OP to count the teeth. He needs to match the front axle. Probably not a 2.76 with a 700R4, final drive would be under 2.

 

[DoubleDingo]

Mebbe 2.76? was the default making 3.08 an option.
I wanna change my answer to 2.76.

The answer is "pickles", always pickles when in doubt

 

[Rusty Nail]

Needs picks
p-i-c-k-s