1998 Ford Expedition Control arms

I looked up lower front control arms for a '98 Navigator and a '98 Expedition. Both show the same part numbers but they're different depending on 2wd or 4wd.

You can look up the part numbers on any of a number of auto parts store web sites to see if they're the same for different years and models. Any salvage yard can do that for you too. They have "Hollander" interchange books that list each part on a specific vehicle with a code number, then you look up that number in the back of the book and it will tell which models and years that part can be found on.