Go to www.helminc.com. They will have it. Dealer just gave me the web address todaywhen I asked the same question for my 2001 F350 SD.
The fuse box for the trailer lights are under the hood (drivers side). Have to look in your owners manual to find the correct fuse.
See attached link to view a free copy of the owners manual.
You can view the 1999 Ford F-250 owners manuals ( both light duty and Super Duty ) online at : www . motorcraft service . com ( no spaces ) Click on Owner Guides
should be down by steering column.check owners manual.
four cycle dryer
The 2007 Ford F-250-Super-DUTY has a 6-speed manual.
The 2005 Ford F-350-Super-DUTY has a 6-speed manual.
The 2010 Ford F-350-Super-DUTY has a 6-speed manual.
The 2001 Ford F-250-Super-DUTY has a 5-speed manual.
The 2010 Ford F-250-Super-DUTY has a 6-speed manual.
The 2009 Ford F-450-Super-DUTY has a 6-speed manual.
The 2003 Ford F-350-Super-DUTY has a 6-speed manual.