The negative post of the battery "ground", goes to the top mounting bolt of the starter. This provides grounding for the engine. There is also a ground cable that runs from the drivers' side of the engine where the bell housing attaches to the firewall below the brake master cylinder but more towards the center of the firewall. This gives you a solid grounding path from the battery's negative post thru the engine and to the cab. All connections must be free of rust and securely tightened. You may have more on your truck but these two are essential.