When doing replacement or upgrading on 1976 – 1979 Buick Opel, the bulb size guide is necessary for you to take the reference.
Jump to corresponding car model with the catalog bellow.

High Beam and Low Beam Headlight1976 – 1978 6014
1979 H6054
Brake1976 – 1979 1157
Dome Light1976 – 1978 57
1979 67
Front Side Marker1976 – 1979 67
Front Turn Signal1976 – 1979 1157
License Plate1979 53
1976 – 1978 67
Parking Light1976 – 1979 1157
Rear Side Marker1976 – 1979 67
Rear Turn Signal1976 – 1979 1157
Tail Light1976 – 1979 1157