I've seen a few Pontiac marked ones, thought if I could find a Buick marked Econometer/Vacuum gauge might be a neat little addition for the skylark. I've never seen a buick one, if they even exist .
FYI: Buick had them integrated in the dash of '75 and up, full size models. Not as spectacular as the Pontiac one though.
I purchased a Pontiac one several years ago. I took it apart and painted the fascia over where it says Pontiac. I just left mine flat black but I am sure you could find a small Buick decal that would look great in the same place! Worked great in my '67 for several years, but didn't care for it as a knee knocker. Mike