Two problems related to automatic transmission cooler have been reported for the 1999 Ford F-150. The most recently reported issues are listed below.
Removed and installed transmission line (filler pipe where you put oil in rusting through) installed transmission dipstick tube. 06/22/2005. Removed and installed transmission filter, transmission flush 08/30/2005. On 02/08/2006 removed transmission, rebuild transmission, installed transmission, flushed transmission cooler. This was caused by the filler pipe(oil input) rusting and letting water into the system. It should not have happened for a 1999 Ford pickup F-150 with 65000 miles, no matter how old or new it was. I have always had Ford trucks or cars and drove them for thousands of miles without the amount of problems I have had with this one, there is a noise in the rear end that I am watching now. . . . . .
All the transmission fluid leaked out while on freeway burned up overdrive and drive there was no warning of any kind when I slowed down in traffic and tried to accelerate the truck went nowhere. In another situation the results could have been worse.