I have a 2001... May not translate... I rebuilt my dash, mostly. Have to tear it down again though similar problem but only when off-road.
Dash is overwhelming, but when you break it down not too bad. Snds like your friend knows well enough to help.
Basic structure / disassembly... You have a skin which lays on a skeleton. There are technical words for it but I forgot them. Pull the lower knee bolsters off. Then the top, and then remove the controls. You may also have to remove A pillar trim.
This exposes the skeleton everything attaches too. You will have vents and various control boxes on top of Skelton. You can remove all those.
You also have to remove the steering wheel. Then the skeleton can come off. This exposes an inner aluminum structure holding steering column, wiring harness etc. On passenger side and center is the air handler for HVAC.
That is as far as I have gone... Hopefully you don't need to do all that. Somebody smarter than I probably knows how to remove it all at once cause the factory installs dash assembled from what I understand.
Long story short... Get yourself felt tape, gorilla tape, foam tape etc... Insulate and take things off that might be source of rattling WHENEVER you take it apart. Also make sure your screws and fasteners are all snug... Don't crank of them but say zero lash and tad more. You can also put small bead of rtv on parts that might cause a rattle or squeak. Apply very small bead, and let it dry before reassembly.
My two cents. Oh one last tip, if every you need to learn, visit local junkyard and disassemble one of the wrecked trucks
