LOL I had a similar sound in mine. Doubtful yours is as simple as mine was but over time and driving the panel under the steering wheel, the one your knee would hit if you lifted it up to the dash, was vibrating... A firm hold and it would stop, I took it off and adjusted the clips and added some foam padding and no more sound.
Like I said, its prolly not that simple, but something to consider. If you can't hear it under the hood with the hood lifted, Its most likely in the cab with you... cricket or not