When doing replacement or upgrading on 1964 – 1995 Chevrolet G10 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 Headlight 1975 – 1977 6014
Back Up Light 1975 – 1977 199
Brake 1975 – 1977 198
Dome Light 1975 – 1977 211-2
Front Side Marker 1975 – 1977 194
Front Turn Signal 1975 – 1977 198
License Plate 1975 – 1977 97
Parking Light 1975 – 1977 198
Rear Turn Signal 1975 – 1977 198
Tail Light 1975 – 1977 198
High Beam and Low Beam Headlight 1978 – 1987 6014
Back Up Light 1978 – 1987 1156
Brake 1978 – 1982 1157
1983 – 1987 2057
Dome Light 1978 – 1987 211-2
Front Side Marker 1978 – 1987 194
Front Turn Signal 1978 – 1982 1157
1983 – 1987 2057
License Plate 1980 – 1987 67
1978 – 1979 97
Parking Light 1980 – 1982 1157
1978 – 1979 1157NA
1983 – 1987 2057NA
Rear Turn Signal 1978 – 1982 1157
1983 – 1987 2057
Tail Light 1978 – 1982 1157
1983 – 1987 2057
Courtesy 1980 194
Map Light 1985 – 1987 912
Radio Display 1985 – 1987 1893
High Beam and Low Beam Headlight 1978 – 1987 H6054
Back Up Light 1978 – 1987 1156
Brake 1978 – 1982 1157
1983 – 1987 2057
Dome Light 1978 – 1987 211-2
Front Side Marker 1978 – 1987 194
Front Turn Signal 1978 – 1982 1157NA
1983 – 1987 2057NA
License Plate 1980 – 1987 67
1978 – 1979 97
Parking Light 1980 – 1982 1157
1978 – 1979 1157NA
1983 – 1987 2057NA
Rear Turn Signal 1978 – 1982 1157
1983 – 1987 2057
Tail Light 1978 – 1982 1157
1983 – 1987 2057
Courtesy 1980 194
Map Light 1985 – 1987 912
Radio Display 1985 – 1987 1893
Low Beam Headlight 1988 – 1991 H4656
1992 – 1995 H4703
High Beam Headlight 1988 – 1991 H4651
1992 – 1995 H4701
Back Up Light 1988 – 1995 1156
Brake 1988 – 1995 2057
Dome Light 1992 – 1994 211-2
1988 – 1991, 1995 578
Front Side Marker 1988 – 1995 194
Front Turn Signal 1988 – 1991 2057
1992 – 1994 3157
License Plate 1995 194
1988 – 1994 67
Parking Light 1988 – 1991 2057NA
1992 – 1995 3157
Rear Turn Signal 1988 – 1995 2057
Tail Light 1988 – 1995 2057
Front Inner Turn Signal 1995 3157
Front Outer Turn Signal 1995 194NA
Center High Mount Stop Light 1988 – 1995 921
Courtesy 1995 212-2
Engine Compartment Light 1992 – 1995 12814
Map Light 1988 – 1991 194
1995 906
1992 – 1994 912
Radio Display 1988 – 1994 1893
High Beam and Low Beam Headlight 1988 – 1995 H6054
Back Up Light 1988 – 1995 1156
Brake 1988 – 1995 2057
Dome Light 1992 – 1994 211-2
1988 – 1991, 1995 578
Front Side Marker 1988 – 1995 194
Front Turn Signal 1988 – 1991 2057
1992 – 1994 3157
License Plate 1995 194
1988 – 1994 67
Parking Light 1988 – 1991 2057NA
1992 – 1995 3157
Rear Turn Signal 1988 – 1995 2057
Tail Light 1988 – 1995 2057
Front Inner Turn Signal 1995 3157
Front Outer Turn Signal 1995 194NA
Center High Mount Stop Light 1988 – 1995 921
Courtesy 1995 212-2
Engine Compartment Light 1992 – 1995 12814
Map Light 1988 – 1991 194
1995 906
1992 – 1994 912
Radio Display 1988 – 1994 1893
High Beam and Low Beam Headlight 1964 – 1974 6014
Back Up Light 1969 – 1974 199
Brake 1964 – 1974 198
Dome Light 1964 – 1968, 1974 211-2
Front Side Marker 1972 – 1974 194
Front Turn Signal 1966 – 1974 198
1964 – 1965 199
License Plate 1966 – 1968 89
1974 97
Parking Light 1971 – 1974 198
1964 – 1968 67
1969 – 1970 97
Rear Side Marker 1972 – 1973 97
Rear Turn Signal 1964 – 1965, 1969 – 1971 1156
1966 – 1968, 1972 – 1974 198
Tail Light 1964 – 1974 198
Courtesy 1964 – 1968 211-2
1973 212-2
1969 – 1972 578