Rear differential

[Rippa's Ram]

What is the easiest way to tell which rear differential I have? 21 1500 Bighorn 5.7 Etorque

 

[Scram1500]

3.92 at 70 mph will be around 2000 rpm, 3.21 will be about 1700 rpm at the same speed. You can also look up the Monroney label and it will list the options

 

[CHeYeNNe71]

Run your VIN

FCA RAM

fcagroup.my.site.com

 

[rick619]

Run your VIN

FCA RAM

fcagroup.my.site.com

Agree with this, lookup your sticker. I always find and download my sticker the day I buy it, good for a reference later. Some MFG's remove that info after a few years. So save it while you can.

Likely easy to guess. It's an option on Bighorn, but I'd say unlikely unless you have other packages (towing) that would suggest you have it.

 

[Paul B]

Run your VIN

FCA RAM

fcagroup.my.site.com

Doesn't work for mine??
Tried several times, states unsupported VIN #.
Paul B

 

[UnloosedChewtoy]

Doesn't work for mine??
Tried several times, states unsupported VIN #.
Paul B

2025s are weird, for some reason. They do not work with that tool. Try this guy's tool. Works nicely for most.

FCA Vehicle Information Tool

What is the easiest way to tell which rear differential I have? 21 1500 Bighorn 5.7 Etorque

Although I feel the build tools above are easier, if you have a 4x4, you can also look at the tag on the back, bottom side of the front differential. The rear tag is probably wiped/unreadable by now, being a 2021, but that front tag is protected a lot better and usually still legible. I know on my previous Rams, the rear tag was usually illegible after only a couple years, but the front tag persevered for many.