They weren't faring so well in that market.
In 2003, Ford introduced the 6.0-liter Power Stroke that replaced the 7.3-liter version.
2005
Around 1984-1985 timeframe
Low sales.
2003
Mainly due to overall lagging sales in the compact/mid-size pickup market. Same reason Ford and GM eventually dropped their compact trucks as well.
The 2005 Ford Thunderbird was the last model year
1997 was the last model year that you could get the 460 ( 7.5 liter ) in the Ford F-250
2011
Chevrolet never made the Cheyenne trucks for public distribution. The Chevrolet Cheyenne was only a concept car made for future models.
G.M. and Chrysler management probably wish that Ford would =)
2010 was the last model year for the Ford Explorer Sport Trac