O/D light flashing means that there is a problem with one of the sensors or the electrically system of the tranny.
Might be hard to retrieve the actually code, since it might not be stored in continuious memory. I take it that the CEL did not come on? It would be worth a try though. To be honest, even though I have a `98 Ford Service CD, there is no talk or mention of the O/D light flashing. On pre OBD-II systems, there was some codes that the O/D light would flash, but on OBD-II systems there is nothing of the sort.
For some more reading, check out some links I have put together.
http://www.geocities.com/yyz81/cd4e/links.html
Please, let us know what you can find about if the system set a hard code and what it was. We can help you alot better from there. Just too many variables to start throwing stones.
Oh yeah! Welcome aboard to CEG.
[EDIT]Thanks for posting that link! I have been looking for it since I lost it some time ago. I am adding back to my current list right now!![/EDIT]
