You will need to consult your vehicle's owner's manual. It should specify the correct refrigerant type and charge amount.
If you don't have the owner's manual, you can try:
* Looking up your truck's specifications online: Use the year, make, model, and trim level to search for specifications. Some websites specializing in automotive repair information might list this.
* Checking with a local auto parts store: They may have access to service manuals or databases with this information.
* Consulting a qualified mechanic: A mechanic will have access to the proper information and tools to properly charge your AC system. This is the safest and recommended option. Improperly charging your AC system can damage the compressor.
Remember, working with refrigerants requires proper equipment and knowledge to avoid injury and environmental harm. Let a professional handle it if you're not experienced.