took truck to dealer, they put weather stripping under trim. didn't work. brought truck in 2nd time shop foreman told me it was probably caused by hood deflector. he told me he taped the deflector and the noise stopped, i asked him to leave tape on so i could verify, the tape was off when i picked truck up, if it was ever on i don't know. other issues with applewood gmc lead me to believe i was lied to.