I think I agree with it being from a late 70's-early 80's Eldorado. It has to be new enough for that model not to offer an AM only one speaker radio and have side window defrosters, so that leaves a really high end car from the late 70's, or a standard car from the late 80's early 90's.
I think that would rule out a 70's Olds.
Look how deep that dash is too...70's cars didn't have a dash that deep, plus those defroster vents are really nice - a basic car from the 70's wouldn't have a grille covering the opening.
Just the depth has me thinking a W-body.
And those speaker openings are for 6x9s!