A few minutes ago I just pulled in from about a 400 mile road trip in my '01 7.3 Excursion. When I pulled in the driveway, I gave it a couple rev's and noticed a rumble/deep vibration that felt like it was coming from under the seat. Almost feels similar to what a worn carrier bearing for the driveshaft feels like, but a deeper rumble and more noticeable. I didn't notice this rumble when on the road trip today, only when I pulled in the driveway and revved it. The only thing that comes to mind is motor mounts, but I feel like I would have noticed that on the trip today. Any ideas? Thanks!