Dash squeaks are hard to find and often times are fixed without finding the actual issue.
I've seen guys use grease, oils, or just take it apart and reassemble it. But what I used to do was every place I saw where two pieces met but didn't have a screw actually holding it down I would put a piece of cloth there. I've used bits of grease rags, but good felt works best. A little glue to keep it there, and you don't want a lot as that will make it hard to assemble.
It takes time, but it will never squeak or rattle again.
2001 HO Cummins powered Dodge 2500
2014 Sierra 346RETS
Nights camped in 2014-28