Rear diff.

[yeahitsbrown]

Can anyone tell me what diff and gear ratio my truck has? 5.7 short box 2WD w NV3500 5spd. I know it's an open diff but I plan on getting a posi unit for it. Just would like to know what posi unit I'd have to order.

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[Purefection]

Look in the glove box at the codes on the sticker. GU6 is 3.42 gt4 is 3.73 g80 is positrac

 

[yeahitsbrown]

Thanks man

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[heavyjunk]

Count the bolts on the diff cover. Not trying to be a smartass here, but GM drive axles are identified by the number of bolts holding the cover on, so... 10 bolts make it a 10 bolt, so on and so forth. As for gear ratio, do what he said ^.... or, there are a couple of web based calculators that you can google, input your tire height and rpm at 60mph in direct(fourth gear in your case) and it will give you an estimate of your ratio......or, pull your diff cover(fluid could prob use a change anyway LOL) and divide the amount of ring gear teeth by the amount of pinion gear teeth. There are a couple other ways too, but these are the easiest that I can remember.

 

[Purefection]

The gear ratio is stamped into the ring gear usually too. A big number and a small number. Glove box is easiest.

And yes. Count your bolts on the cover. Will be 10 or 14

 

[yeahitsbrown]

Thanks for the info guys! I have a 3.42 ten bolt.

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