I'm assuming you have a 4.3 liter engine, but regardless of size the first thing I would check is the battey to insure its properly charged
if battery is good try this:
If it is a manual try pull starting it
to do that you get somebody to pull the truck while your holding in the clutch and gears set to 2nd and as your being pulled (leave the key on as well) slowly let off the clutch
if battery is good try this:
If it is a manual try pull starting it
to do that you get somebody to pull the truck while your holding in the clutch and gears set to 2nd and as your being pulled (leave the key on as well) slowly let off the clutch