Well the hardest one is the piece behind the steering wheel, extending over the vents to the glove box. There are three screws on the upper part of the housing for the center air vents. Remove those. Then you'll have to remove your instrument cluster.
To remove that, you can either remove the carpeted area right above the pedals (right where your shins would be) and push it out from underneath, OR you can get two pieces of stiff wire (hanger worked for me) and bend the ends a small (1/8-1/4") 90 degrees. Then insert them at a about 10 o'clock and 2 o'clock position between the cluster and the dash. Or right after the "curve" in the cluster where the top turns down into the sides. After inserting the wires, turn the bent ends of the wire towards the cluster and pull out. It'll require a firm pull so don't be scared. Then disconnect all the wiring. Don't worry about this because everything is either marked or the plugs are specific to the hole in which they go in.
Then after that is done, there are two plastic nuts on the backside of the wood. Feel around with your fingers to locate them. What I did here is take a socket, can't remember the size...think it's a 7mil...put an extension on it and just turn the extension with my hands. There is not a whole lotta room back there to be swingin a ratchet around. Maybe a 1/4" ratchet would work...
Now ya only got one nut left. You have to take out the vent to the left of the wheel. You have to lift up on the little metal tab on the inside and it pops out. There is another plastic nut on the left side.
After all that is done...the hardest part is actually getting the thing to come out. Ya kinda have to jiggle it here and there. Just be careful not to break it....or break the new one when installing it, since this piece is very fragile.
I have not removed the other two pieces on the dash. I imagine the glove box is quite easy. Remove the plastic cover on the back and the nuts are probably right there. As far as the piece all the way to the right... I'm guessing there is a nut inside where the air vent is like the other side, but beyond that I'm not sure. If ya can't figure it out...let me know and I'll look it up in my service manual.
Good luck and hope this helps some. If ya need me to clear something up or whatnot, just ask.
'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.
"A Mercedes-Benz is like a fine wine, it only gets better with age."