How do you know if you have 3:21 or 3:92?

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shaner82

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Hemi and 8sps only come with 3:21s or 3:92s for some reason.

I had a 2013 sport that had the Hemi, 8 speed and 3.55. Perhaps that's changed since then, but it was definitely an option back in 2013
 

BWL

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When I asked a psychic she said 3.21, but the build sheet says 3.92. How do I know which is correct? The build sheet had the correct color and vin#, but the psychic knew I had somebody close to me die and that I've used a telephone so both seem credible.
 

Svetla

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Hello my friends. 1C6RR7LT4JS247787
3.92 or 3.21?
 

JB1

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Crawl underneath the back of your truck and look for a sticker under your rear differential on the drivers side.

Here’s mine with 3.92’s

F4886269-951C-4EBE-A093-FE3C20E9DEE3.jpeg
 

Svetla

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VIN decoder gives incorrect information. I write my body number and I have 3.21 defined. this is incorrect since my pair is actually 3.92. I do not understand why you need a pair of 3.92. at 60 mph, it's already 2000 rpm. increased gasoline consumption.

Screenshot_2020-03-18-02-41-04.png
 

Dieselhorses

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Let me ask this... Or if you know a forum that explains this... If I have 3.21 gears (what it said on axle) then what do I need to change in differential for 3.92 gears? And I assume I have to change something in front also?
 

Wild one

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Let me ask this... Or if you know a forum that explains this... If I have 3.21 gears (what it said on axle) then what do I need to change in differential for 3.92 gears? And I assume I have to change something in front also?

A wallet full of money.You need to buy a new or different front diff assembly with the gears you want,as you can't ghange gears in the later ZF front diffs.Rear is just a standard rebuild with the ring and pinion you want and a master rebuild kit,hit up Matt at Moes a vendor on here for everything you need for the rear diff rebuild.Another option is to buy both diffs from a wrecked truck as complete units and swap them in,then sell your existing diffs to recoup some of your money
 

Dieselhorses

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A wallet full of money.You need to buy a new or different front diff assembly with the gears you want,as you can't ghange gears in the later ZF front diffs.Rear is just a standard rebuild with the ring and pinion you want and a master rebuild kit,hit up Matt at Moes a vendor on here for everything you need for the rear diff rebuild.Another option is to buy both diffs from a wrecked truck as complete units and swap them in,then sell your existing diffs to recoup some of your money

Thanks. I realize now that gas mileage may be a little more important than doing burnouts. I did find this calculator that was interesting. Looks like it changes gear ratio automatically as tire size goes up.

https://www.intercotire.com/tire_size_change_gear_ratio_calculator


Sent from my iPhone using Tapatalk
 

Narg

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I have 3.21 and the passing ability is more than I had before. I'm happy.
 

Narg

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Could also have 3.55's.

Like said, the vast majority of 8spds have 3.21's with a mix of 3.55s and 3.92s in there.

Uh... No. V6 have the 3.55 by default. Can't get the 3.55 in the V8 at all. Most V8's have the 3.92 from my experience. I had to fight to get a 3.21. Happy with what I got. Not recommended, but what I wanted and happy.
 

PoMansRam

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Uh... No. V6 have the 3.55 by default. Can't get the 3.55 in the V8 at all. Most V8's have the 3.92 from my experience. I had to fight to get a 3.21. Happy with what I got. Not recommended, but what I wanted and happy.

Can you point me to that source?

I've not seen this in any standard option lineup 4th gen or classic Ram 1500. I know 3.55's were an option on my brother's 2019 Ram 1500 classic w/ pentastar and oddly, it was like a ~$55 option. Ridiculously cheap.
 
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crash68

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V6 have the 3.55 by default. Can't get the 3.55 in the V8 at all. Most V8's have the 3.92 from my experience. I had to fight to get a 3.21
Only the EcoDiesel 3.0L V6 came standard with 3.55 as 3.21 was not available for that engine. Both the 3.55(Pentastar) and 3.92(Hemi & EcoD) were optional gearing that was either customer added or part of a trim package (Outdoorsman, Rebel, etc)
The vehicles found on dealer lots will usually have what the general demand of their customers. I can probably show you several hundred Ram trucks sitting on local lots with the standard 3.21 gearing.
 

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