I was on the freeway and lost every gear but 4th in my 96 xj with manual tranny. Ive oiled up both diffs., replaced master/slave clutch cylinders, changed clutch and still i can move my shifter around freely without stepping on the clutch pedal and i still get no gears.

 

It's stuck in 4th, no matter the position of the shifter? It's possible the tip of the shifter has become disengaged from the shift rods.