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3.21 to 3.92 gear change

kunkernator

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Hi all, new to the forum, got a couple questions.

Im sure this has been covered before, although i cannot find specifics on part numbers.

I own a 2019 Ram 1500 New body, Hemi eTorque, 4x4, 3.21 axle

I have come to the realization that either sooner or later, i will be swapping the gears over to a 3.92. i understand that the front differential assembly needs to be changed, while the rear ring and pinion can be changed.

I found this part number to be for the "new" 3.92 differential assembly that i will need: 68349705AD

And this part number for the rear 3.92 ring/pinion set: 68088164AD

My questions as follows:
Are those the correct part numbers if i go with Mopar parts?
Is that front differential assembly the only one that will fit my truck, or will one out of a used 4th gen truck fit as well?
As for aftermarket options for the rear, i am only finding 3.90 ratio sets, are these correct?
Would you prefer aftermarket or factory parts for the rear?
When i do the swap, is a tuner necessary, or can FCA reflash my truck for the new ratios?

Thanks all in advance!
 

Zeronet

Ram Guru
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Jul 5, 2018
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I changed the rear gear on a 4th gen Ram 4x2. Back then it cost me about $300 for parts (that I purchased and supplied to the shop) and $900 for labor. Took them a full day to install. If it had been a 4x4 I would have just traded the truck for something similar with the gear ratio I wanted.

Cost-wise probably a wash, less risk of problems and loss of warranty on those parts. Unless you have a lot of money in mods that are not easily removed, maybe consider selling yours and buy what you want/need?
 

kunkernator

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I changed the rear gear on a 4th gen Ram 4x2. Back then it cost me about $300 for parts (that I purchased and supplied to the shop) and $900 for labor. Took them a full day to install. If it had been a 4x4 I would have just traded the truck for something similar with the gear ratio I wanted.

Cost-wise probably a wash, less risk of problems and loss of warranty on those parts. Unless you have a lot of money in mods that are not easily removed, maybe consider selling yours and buy what you want/need?

Appreciate the response, but cost wise, is no concern to me, i can get the OEM parts for ~$1500 and labor is free. Im not concerned regarding the warranty, i will most likely be doing this toward the end of my warranty.

If anyone else has any insight on my questions i appreciate it. Thanks.
 

dts828

Ram Guru
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Dec 28, 2019
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Atlanta, GA
Hi all, new to the forum, got a couple questions.

Im sure this has been covered before, although i cannot find specifics on part numbers.

I own a 2019 Ram 1500 New body, Hemi eTorque, 4x4, 3.21 axle

I have come to the realization that either sooner or later, i will be swapping the gears over to a 3.92. i understand that the front differential assembly needs to be changed, while the rear ring and pinion can be changed.

I found this part number to be for the "new" 3.92 differential assembly that i will need: 68349705AD

And this part number for the rear 3.92 ring/pinion set: 68088164AD

My questions as follows:
Are those the correct part numbers if i go with Mopar parts?
Is that front differential assembly the only one that will fit my truck, or will one out of a used 4th gen truck fit as well?
As for aftermarket options for the rear, i am only finding 3.90 ratio sets, are these correct?
Would you prefer aftermarket or factory parts for the rear?
When i do the swap, is a tuner necessary, or can FCA reflash my truck for the new ratios?

Thanks all in advance!



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