turn sig flasher

Older cars had the fuse block under the dash and the flasher would be there as well on the block as well. Newer models not sure, probably under the dash or on the fuse block (later models usually located in the engine bay), but pick up a haynes or chiltons manual should be noted somewhere.

That info USED to be in the Owner Manual

Your truck does not have a "conventional" turn signal flasher. The flasher relay looks like a typical relay rather than a flasher and is located in a relay block behind the centre of the instrument panel (dash board, actually - depends on nomenclature).

Be aware that it is more common to have concerns with the multifunction switch and/or wiring - especially if tilt steering is involved.