* 4.3L V6: The recommended gap is typically 0.045 inches (1.1 mm).
* 2.5L I4: The recommended gap is typically 0.035 inches (0.9 mm).
To be absolutely certain, check your owner's manual. It will specify the correct gap for your particular engine. If you don't have the manual, you can often find a digital copy online by searching for "[Year] Chevy Astro owner's manual [Engine size]".