It reads like the cable's sheath is broken.
The sheath on a cable like this, like a bicycles brake cable, sets the travel the cable has.
The sheath ends must be fixed, for cable to have equal movement at each end, and the sheath in between must remain the same length, if it breaks or cracks the movement at one end is shortened.
P R N D 3 2 1
If you lose one end or the other then cable movement has shortened, like P R N
Look where the cable comes out of the firewall and bends back to go to the transmission shift linkage, that is most likely spot for sheath to break, and cable will be visible or you will see that one end of the broken sheath has slide inside the other end.
The shift tube could also be broken, that would be the "slop" you feel, and it may have broken because of shift cable issue and the extra force applied trying to get proper operation.
Last edited by RonD; 08-09-2015 at 11:17 PM.