My guess is that you have a Dana 30 upfront and a Dana 44 in the back. They have different shaped pumpkins, so it's easy to tell the difference. 44s are less round. As to the gear ratio, either you can find it on the build sheet, axel tags or you can count how many times the driveshaft rotates for each rotation of the tire.
Post a picture of the front. Unless you or a PO has done some serious mods, you have a D44 rear and D30 front. You'll have to send an email to Jeep customer service with your VIN number requesting a factory build sheet to find out your gear ratio. Or you could jack the Jeep up and count the driveshaft and tire revolutions.
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