I have a 2007 jk x and i bought it used on the build sheet of the car it does not say i have a posi. but today i was playing in the snow put it in 2 wheel drive and went for it and both tires spun how can this be..... normal if you have a open diff the right wheel will only spin but i had both tires going had the door open and looking. any thoughts

 

Here's how to tell: Jack the rear up by the center section and support the axle with jack stands. Put the Jeep in park or in gear if it's a manual. Grab a tire and see if it'll turn. If it will, you ain't gotta posi. If it won't turn you do. It's normal for a standard opened faced differential to spin one, the other or both on slippery surfaces such as snow mud ice and the like.