2002 Chevy Avalanche rocker arm tapping noise

It is possible, but you would want to have oil pressure checked with a mechanical gauge first.

Other possibilities, are collapsed lifter, bent rocker arm, bent pushrod, or clogged oil galley.

If you want to do it yourself, start with oil pressure check (mechanical gauge), then remove valve covers and inspect for any areas on valve train that appear "dry". Check rockers for excessive play.