if they haven't been fooled with before, there are metal clips that hold the vents into the bezel on each side and in the middle of the two (if they are anything like my 78's). those clips really need to be removed FIRST to get the vents out of the mountings. they remove from the back making it pretty tough to try to get the vents out the front. the vents also are "hinged" with little pins that extend on each side to allow them to rotate up and down. needless to say, that makes them remove from the back also. (the clips keep them in their "tracks"). all the "cautions" above are VERY REAL. the lamp housing that afixes to the top of the bezel requires that the bottom of the bezel be slid out first to allow for clearance. i know it might be a real pain, but if you can remove the radio (from the back), it will make the whole job a bit easier by allowing the bottom of the bezel to be pulled forward (after removing the bolts that hold it to the console) thereby lowering the top of the bezel enough to clear the dash pad with the lamp housing.
steve