hillbilly customz

Im trying to get my new to me 1988 cherokee road worthy. Ever since Ive had the jeep it wouldnt go into park and barely reverse. I yanked all the nasty interior out over the weekend to bedline the floor, so since that is done I figured I would try to figure out if it was the shifter or shifter cable needing adj. The shifter didnt work real smooth and the button was real loose feeling, so I yanked the one out of my parts jeep and it is much smoother. Get it all hooked up and still the same thing. Then I notice it is the cable that is going up under the dash. I ran out of time tonight and was hoping someone could tell me exactly what that cable is, and how to adjust it were I can go into park. Im new to the cherokees and havent had a chance to order a manual for it yet.