The 1994 Ford Ranger didn't use a single brake line size throughout the entire braking system. Different sections of the brake lines will have different diameters. You'll need to consult a repair manual specific to your 1994 Ford Ranger (including engine size and trim level) to find the exact sizes for each section. These manuals usually have detailed diagrams showing line routing and sizes.
Without that information, it's impossible to give you a definitive answer. Trying to determine the size by visual inspection alone can be inaccurate and potentially dangerous.
