More than likely R-12 is the freon agent in the air conditioning system, it might have the R-134. Normally when R-134 refrigerant is used at least one sticker identifying the new stuff (for that time)will be on the vehicle. Hope this helps, Steve
The freeze plugs on the 1994 Ford Ranger have locations that vary slightly depending on the engine choice. On most trucks the freeze plugs are on the engine block below where the spark plugs are located.