I have the dash noise too, so I did as you suggested. I have the jacks down and slides out, so road testing right now is out. I found that there is a square tube that runs about 3/4 of the way along the joint. There were also four (useless) factory screws missing. In the end, I added a couple more. I wish I knew how to rotate the pix.
The one shot shows the old and new screws. Thanks for the tip