How do you set the timing on a 1998 gmc c6500 topkick with 7.0 liter?

To set the timing on a 1998 GMC C6500 Topkick with a 7.0-liter engine, first ensure the engine is at operating temperature and then turn off the ignition. Locate the timing marks on the harmonic balancer and the timing tab. Use a timing light connected to the number one cylinder spark plug wire to check the timing. Adjust the distributor until the timing mark aligns with the specified degree mark (usually around 0-10 degrees BTDC) on the timing tab. After adjustments, recheck the timing to confirm it's set correctly.