If I remember correctly, it is by the steering column, under the dash, kind of buried. I remember it as a round plug and I think it's on the left, but not sure. We upgraded from our 98 Discovery several years ago. I think there is also one on the back of the coach, around the radiator, but I'm not sure. There is one there on my Expedition along with the circular one under the dash. Hope you find it OK. We really like our Scanguage D.
Jim and Lynda, (Sophie, Jake, attack trained killer Shi-Tzus :-))
2003 Fleetwood Expedition 38N 2005 Saturn Vue