I believe he said they were off of a Skylark, which I doubt. After googling a few different 66 Buicks, my money in on the 1966 Le Sabre being the origin. They might be off a Special, but the pictures of the Special for that year make the ports look like three different parts on each side of the car, just like my 65.
I asked for part number and had no reply, so I suggest passing on these unless you know for sure what they are.