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I suspect the NV3500... but not certain.
Go here: https://www.jeep.com/webselfservice/jeep/index.html
On the left side menu, under "Your Vehicle," click on "Equipment Listing."
Then enter the VIN number of your KJ - it will spit back your build sheet which should tell you which transmission came with your KJ.
If that doesn't work, then you can always use this form (https://www.jeep.com/webselfservice/jeep/EmailPage.html) to request that a build sheet be sent to you - both methods have worked for me.
(Cheers)