DOT 3 brake fluid - pretty much a universally specified, and readily available brake fluid.
NOTE: The Owners Manual contains illustrated procedures for checking/filling brake fluid - and the specified fluids for the vehicle.
See "Related Questions" below for a free sources of online Owners Manuals
For a 1993 Ford Ranger : ( DOT 3 brake fluid )
DOT 3 brake fluid
DOT ( 3 ) brake fluid
DOT ( 3 ) brake fluid
For a 1984 Ford F-150 : DOT 3 brake fluid
DOT ( 3 ) brake fluid
DOT 3 brake fluid
DOT 3 brake fluid
DOT ( 3 ) brake fluid
DOT ( 3 ) brake fluid
Regular DOT3 brake fluid
DOT ( 3 ) brake fluid meeting Ford specification ( ESA-M6C25-A )