One problem related to transmission not go into gear has been reported for the 1999 Ford F-150. The most recently reported issues are listed below.
Would be driving and would shift into 3rd gear, and it would make grinding noises. Then, locked out other gears. Would either stop or slow down vehicle and shift into another gear. Have taken vehicle to dealership and informed by mechanic engine not long enough to turn gears in transmission. Not able to repair problem. A technical service bulletin on transmission gears.