tommyddsr.... I got tired of researching for polyurethane body mounts for the Expedition, but they are out there. As for today there is no company besides Ford and Dorman that produces Expy OEM body mounts. They sell polyurethane body mounts for the F150 as they are the same fittings as Expy's. When I found this out it was too late I've already purchased Dorman's, too much hassle for me knowing these mounts will last probably another 8-10 years for a truck that has 200K plus miles on it. By then I probably purchase another Expy.
If your mounts are rattling or rotting it's definitely time to change. I don't know if they are all the same you need to look at actual and compare pictures of it, I'm not sure about the front engine or the rear where your spare tire is at.