To find the correct bolt size, you must either:
* Consult a repair manual: A Haynes or Chilton manual specific to your 1994 Ford Bronco will have the exact specifications.
* Check the parts diagram: Use a parts website like AutoZone, Advance Auto Parts, or Napa Auto Parts. Enter your Bronco's VIN or select your year, make, and model. Find the brake caliper diagram and it should list the bolt sizes.
* Remove a caliper and measure the bolts: This is the most direct method, but requires removing a caliper (and potentially some care to avoid damaging threads). Once removed, you can measure the bolt thread size and length.
Don't rely on generalized information found online. Using the wrong size bolt could lead to brake failure, a very dangerous situation. Always use the correct parts when working on your brakes.