A few days ago I posted the same ? but I put down that it was a 1990 because the questionaire only goes that far back. There's no current running thru the fuse.
1969 f-250 gauges don't work/fuse not blown out. on 1990 Ford F-250
If you e-mail me I can e-mail you the wiring diagram for your 1969 F-250. firstname.lastname@example.org
I have a 72 f250 sometimes the same thing happenes...for me it ended up being the ignition switch. worth looking at. theres not very many componets in these style trucks electrical system.