Two problems related to transmission slip out of gear have been reported for the 2001 Ford F-250. The most recently reported issues are listed below.
While driving at approximately 50 mph transmission shifted into second gear. Transmission is an automatic. Transmission would not shift out of second gear. The vehicle would not move at all when put in reverse. There was nothing abnormal noticed with transmission prior to this occurrence except a unexplained thud noise that I had taken the vehicle in for during the initial warranty period. I was told that this was a normal characteristic of the vehicle. Transmission had to be replaced per Ford dealership. Ford dealership installed remanufactured transmission. This transmission was faulty and had to be replaced with another remanufactured transmission.
As I was driving my Ford F-250 sd taking my child to school, there was a loud bang and the truck felt like it hit a brick wall. It would only do this when shifting out of 2nd gear. Powerstroke with a 4r100 transmission. Dealer states that the drum or "mechanical diode" has went out, so they replaced with a "sprague diode", at a cost of 1500. 00. There have been numerous reports of this "mechanical diode" breaking due to Ford using bad parts. I called Ford and ask for reimbursement, but was denied. Truck had 64,000 miles when this happened. It is very well documented on various websites about this defect, but Ford seems to deny it. The dealer was very good to work with and is the same dealer that I have do all my service work.