Therefore, there's no single answer to your question about the transmission fluid. To know what fluid to use, you must first determine if your truck actually has a manual transmission. Check your owner's manual (if you have it) or the sticker on the driver's side doorjamb (it should list the transmission type).
If you *do* have a manual transmission (unlikely but possible), the recommended fluid will be specified in your owner's manual. It would likely be a GL-4 or GL-5 gear oil, but the specific viscosity (e.g., 75W-90, 80W-90) will depend on your truck's specifications. Using the incorrect fluid can damage your transmission.
