Since you've owned your truck for 8 years, this is a recent problem, right? Did you work on or replace anything just before the problem appeared? If so, then the problem just might be with the new part or wiring to or around it. New carb? Did you hook the electric choke to a switched 12 volts? If not, it will drain the battery. A good way to find your current drain is to disconnect one side of your battery. Put a light bulb in series with the battery cable and battery post. I use a cheap test light (looks like an ice pick with a lamp in the handle) with one test lead. After hooking it up if you've got a current drain the lamp will glow. Start pulling fuses one at a time until the lamp goes dark. When that happens, you have found the circuit that is giving you problems.
