i have a 98 ford 4x4 f159. it won't go into gear. what could be my problem?

 

Oh I am so sorry but you have to give more details. Starting with all your specs and what happens when you try and shift into gear.

 

One possibility is that when you push down the brake pedal, the truck is not recognizing this and won't allow the shifter to move out of park(auto trans). I believe there is a switch that is activated when you push down the brake pedal and this allows the gear shift to move out of park. If the switch is bad, the shift lever won't move.

 

Well I guess it would help to know if the truck is a manual or auto... If it is auto, I would look into dewman's idea. If it is manual, if you notice that the clutch pedal is rather light, I would say the slave cylinder went bad.