One problem related to overdrive light on has been reported for the 1999 Ford F-350. The most recently reported issues are listed below.
Takata recall. I was driving down the road and my truck shut off randomly my overdrive light started flashing after this and continued to flash and still shuts off so I replaced my fuel filter, cps sensor and it still shuts off. It's like I'm goin down the road and it stalls. It does it more than once when I'm driving I just shut it off and start it again.