I believe it’s a Ford F150. But they aren’t doing as much product placement as they were in earlier seasons. Plus, at the start of this “day,” Jack was living a secret life in hiding. I still think he had a pickup, though.
On a somewhat related note, Mulder and Sculley always drove a standard government-issue Ford Taurus.
Anyhow, I write all this in the hopes that I will neither be killed nor forced to kill anyone. But if I must die, I hope I don’t go the way…
[...spoilers ahead...]