To find it, you'll need to consult your owner's manual. The location varies slightly depending on the year and specific transmission model. The manual will show you exactly where it is, and likely specify the type and amount of transmission fluid required. Attempting to find it without the manual could result in mistaking another plug for the fill plug.
Important Note: Working on a vehicle's transmission is generally complex and requires mechanical expertise. If you are not comfortable with this task, it's highly recommended to take your truck to a qualified mechanic for transmission service. Incorrectly adding or servicing the transmission fluid can cause serious damage.
