The Fleetwood, Roadmaster, and maybe the Olds Custom Cruiser has the panel on the drivers side.
I'm not sure about the Custom Cruiser because I was in a junk yard that had a Custom Cruiser and laying a few feet away was a drivers side under dash panel. Guessed that it came out of the Cruiser, but can't be sure.
I got one out of a Fleetwood and the one from near the Custom Cruiser and neither one fits the 94-96 Caprice/Impala dash. I forget which one it is, but one goes all the way across to almost meet the passenger side panel.
The opening for the courtesy light doesn't line up with the the light on my 95 Caprice dash, but thats an easy fix, the light just attaches with one screw and could be moved to match the panel and its possible that I actually have my light mounted to the wrong screw hole.
The other problem is were the panel meets the dash. One has screw holes that pretty much only line up on the front of the dash which would be kinda ugly, the other panel has the clips like our passenger side panel, but theres nothing on the drivers side to clip them to.
I plan to modify one to make it work if I can get it to look factory and be easy to snap out for access, just haven't been able to mess with it. Also both panels must have came out of cars that had a smoker so I've got to replace the foam or soak it in Odor Ban first and thats another reason I haven't messed with it yet.
Another thought about the noise though. I don't notice any noise coming from that area of my 95 now without the panel and on my 92 and 96 model I did hear noise. The difference with this 95 is during the rebuild before I mounted the dash structure to the A pillars and fire wall, I stuffed the inside of the A pillars with as much insulation as I could get. You can remove the lower trim panels off the A pillars and fill two cavities from the bottom and it makes a huge difference on noise. Just leave room behind the wire going to the door push pin that triggers the dome lights. When the door closes it pushes the pin and attached wire back into the A pillar, so don't push insulation tight against the wire.
On the vehicles with the drivers side under dash panel, one of the bolts on the gas pedal bracket has a threaded section on top of the hex head and a plastic wing nut I belive retains the under dash panel to this bolt. So if you do this mod, you can can check out some junk yards for this bolt. My 92 Caprice has it and the 93 had it also with out the panels, so GM stuck it in all of them during the years the Roadmasters and Caprice were the same dash 91-93.
The lower dash panel has a notch for the brake pedal arm and a curved indention for the steering column.
I can take pictures of both if you want me to post them here?
Since my car is side lined with trans problems, maybe I can take the time to see which panel I can make fit my 95 Caprice dash.