It depends on the bronco model. The old type of freon was phased out.
If its an older truck it would have been R-12. But R-12 is not avalible, you will have to convert it to R-134a. Newer trucks are R-134a.
All cars after 1992 use the same freon. 134a is used in your truck. If you are just low on freon, then topping it off will work just fine. If it blows kind of cold air, filling it will work. Otherwise, it's shop time.
The type of freon you should be using in a 1994 bronco is R-134a. and the quantity id 28 ounces. this should be the same for all of the engine sizes of that model.
Well due to current regulations the vehicle should be recharged with r134a style refrigerant. If the car has the old system it should be purged and retrofitted by a professional.
Well, seeing that the model is 1994, you are better off trying to find something in that grade: 5.8" 6LT freon should be used. Try to find the similar model