One problem related to steering pinion shaft has been reported for the 1998 Ford F-150. The most recently reported issues are listed below.
Steering shaft cracked at the base where connected to the steering box. I lost my steering completely. Thankfully I was pulling into my parking space at work and was not driving on a road or traveling at a higher rate of speed. I have the old part and was told by the mechanic who is fixing the vehicle to report the incident as in their opinion it is a mechanical defect that may have had deadly consequence. My vehicle is a 1998 Ford f150 and has approx 99,000 miles on it. Although the vehicle is older, it certainly is not the oldest vehicle on the road and I have always maintained it and have never used the vehicle for any off road or hard use.