When doing replacement or upgrading on 1967 – 1995 Chevrolet G20 Van with 2 round headlamps rectangular 4, 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 Headlight1975 – 1977 6014
Back Up Light1975 – 1977 199
Brake1975 – 1977 198
Dome Light1975 – 1977 211-2
Front Side Marker1975 – 1977 194
Front Turn Signal1975 – 1977 198
License Plate1975 – 1977 97
Parking Light1975 – 1977 198
Rear Turn Signal1975 – 1977 198
Tail Light1975 – 1977 198
High Beam and Low Beam Headlight1978 – 1987 6014
Back Up Light1978 – 1987 1156
Brake1978 – 1982 1157
1983 – 1987 2057
Dome Light1978 – 1987 211-2
Front Side Marker1978 – 1987 194
Front Turn Signal1978 – 1982 1157
1983 – 1987 2057
License Plate1980 – 1987 67
1978 – 1979 97
Parking Light1980 – 1982 1157
1978 – 1979 1157NA
1983 – 1987 2057NA
Rear Turn Signal1978 – 1982 1157
1983 – 1987 2057
Tail Light1978 – 1982 1157
1983 – 1987 2057
Courtesy1980 194
Map Light1985 – 1987 912
Radio Display1985 – 1987 1893
High Beam and Low Beam Headlight1978 – 1987 H6054
Back Up Light1978 – 1987 1156
Brake1978 – 1982 1157
1983 – 1987 2057
Dome Light1978 – 1987 211-2
Front Side Marker1978 – 1987 194
Front Turn Signal1978 – 1982 1157NA
1983 – 1987 2057NA
License Plate1980 – 1987 67
1978 – 1979 97
Parking Light1980 – 1982 1157
1978 – 1979 1157NA
1983 – 1987 2057NA
Rear Turn Signal1978 – 1982 1157
1983 – 1987 2057
Tail Light1978 – 1982 1157
1983 – 1987 2057
Courtesy1980 194
Map Light1985 – 1987 912
Radio Display1985 – 1987 1893
Low Beam Headlight1988 – 1991 H4656
1992 – 1995 H4703
High Beam Headlight1988 – 1991 H4651
1992 – 1995 H4701
Back Up Light1988 – 1995 1156
Brake1988 – 1995 2057
Dome Light1992 – 1994 211-2
1988 – 1991, 1995 578
Front Side Marker1988 – 1995 194
Front Turn Signal1988 – 1991 2057
1992 – 1994 3157
License Plate1995 194
1988 – 1994 67
Parking Light1988 – 1991 2057NA
1992 – 1995 3157
Rear Turn Signal1988 – 1995 2057
Tail Light1988 – 1995 2057
Front Inner Turn Signal1995 3157
Front Outer Turn Signal1995 194NA
Center High Mount Stop Light1988 – 1995 921
Courtesy1995 212-2
Engine Compartment Light1992 – 1995 12814
Map Light1988 – 1991 194
1995 906
1992 – 1994 912
Radio Display1988 – 1994 1893
High Beam and Low Beam Headlight1988 – 1995 H6054
Back Up Light1988 – 1995 1156
Brake1988 – 1995 2057
Dome Light1992 – 1994 211-2
1988 – 1991, 1995 578
Front Side Marker1988 – 1995 194
Front Turn Signal1988 – 1991 2057
1992 – 1994 3157
License Plate1995 194
1988 – 1994 67
Parking Light1988 – 1991 2057NA
1992 – 1995 3157
Rear Turn Signal1988 – 1995 2057
Tail Light1988 – 1995 2057
Front Inner Turn Signal1995 3157
Front Outer Turn Signal1995 194NA
Center High Mount Stop Light1988 – 1995 921
Courtesy1995 212-2
Engine Compartment Light1992 – 1995 12814
Map Light1988 – 1991 194
1995 906
1992 – 1994 912
Radio Display1988 – 1994 1893
High Beam and Low Beam Headlight1967 – 1974 6014
Back Up Light1969 – 1974 199
Brake1967 – 1974 198
Dome Light1967 – 1968, 1974 211-2
Front Side Marker1972 – 1974 194
Front Turn Signal1967 – 1974 198
License Plate1967 – 1968 89
1974 97
Parking Light1971 – 1974 198
1967 – 1968 67
1969 – 1970 97
Rear Side Marker1972 – 1973 97
Rear Turn Signal1969 – 1971 1156
1967 – 1968, 1972 – 1974 198
Tail Light1967 – 1974 198
Courtesy1967 – 1968 211-2
1973 212-2
1969 – 1972 578