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2015-2016 How to identify which differential is installed.

5K views 7 replies 7 participants last post by  BSAGSA 
#1 ·
I have checked out the various postings about the different differentials in the JK series. I'm considering a demo/rental Sahara that the actual sticker indicates has the 3.73 differential installed. However, the build sheet/equipment listing per jeep.com Jeep - Contact Us indicates only the 3.21 differential.

Is there a way to determine from looking at the differential(s) any tags that would indicate which option is actually installed? This is on a dealer lot.

Any help would be much appreciated.

jd
 
#2 ·
A dealer would be able to tell you. Go to a Jeep dealer with the serial number and have him print off the spec sheet for the Jeep your looking at, it tells you everything it came with. They came with 3.21 and the 3.73 was an option but you already knew that.
 
#3 ·
Personally I would take the Jeep on a test ride to my house and perform the following:
Chock the front and one rear tire.
Raise the the other rear tire.
Mark the drive shaft.
Put Jeep in neutral.
Spin the raised tire 2 rotations and count the drive shaft rotations. Just over 3 drive shaft revolutions = 3.21, 3 3/4 = 3.73.
Can be done on front or rear axles just place chocks accordingly.
If you do the front no need to put in neutral. On either axle the opposite tire must not turn or results will be inaccurate.
 
#4 ·
There are no tags on the diffs. If you're looking at a stock Sahara on a dealer lot and it has the window sticker, 3.21's will be listed as standard equipment. If you look at the option list you'll see 3.73's if it has them. The window sticker will always indicate 3.21's if that's the "standard" dif. on most model JK's. A Rubicon window sticker for example won't indicate 3.21's.
 
#5 ·
^^^This!!! 2006 was the last year for Diff ratio tags.
 
#8 ·
This link will give you all the installed options including what gear ratio is on your Jeep.
https://jeep.custhelp.com/app/jeep/eqlisting_detail/session/L3RpbWUvMTM5MzY0MzI4OC9zaWQvWGxOMmc2T2w=

This ^^.

If you are looking at a used Jeep this is a key link to have on your phone. It doesn't trll you if the limited slip's clutches are still good, etc. but at least you know what it started with from the factory.

I print the build sheet off for my Jeeps to keep with my sticker for when I decide to finally sell.
 
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