03 Silverado dash noise

Uncle passed away was given his 03 Silverado 2500 reg cab, with 13000 miles on it. Ive noticed that when on the freeway at speeds 55 and higher theres a very noticeable and annoying sound that comes from the passanger side dash that sounds like crinkling paper or something flapping extremely fast. This is always more noticeable when its windy outside plus the higher speed, Im stumped and really dont want to pull the dash apart to investigate.I think there is a pass/side air bag, is it poss that some type of airflow is getting in some where to do this or am I off target,Its a very distinct crinkling sound and is making me NUTS! :screwy:

you might try pulling your cabin air filters; there's a chance there's a leaf or something in there. Do a search on this forum for "cabin air filter"