There was one made using a 2001 Explorer. The XP8 was discontinued when Ford changed to a new platform for the 2002 Explorer.
Lack of sales were the main reason for it not going on in life. Too bad, as I would like to have seen a 4.6 XP8 with the Saleen SC kit on it, and would have ordered one.
They have come WAY DOWN in price on the secondary market. Buyer beware, as replacement parts are next to impossible to come by.