When doing replacement or upgrading on 1978 – 1988 Audi 5000 4000 Quattro CS S, the bulb size guide is necessary for you to take the reference.
Jump to corresponding car model with the catalog bellow.

Low Beam Headlight 1980 – 1981 4652
1982 – 1984 H4656
High Beam Headlight 1980 – 1984 H4651
High Beam and Low Beam Headlight 1985 – 1987 9004
Back Up Light 1980 – 1987 1156
Brake 1980 – 1987 1156
Dome Light 1980 – 1981, 1985 – 1987 578
1982 – 1984 6411
Front Side Marker 1980 – 1987 12256
Front Turn Signal 1982 – 1984 1157
1980 – 1981, 1985 – 1987 P21/5W
License Plate 1980 – 1987 T4W
Parking Light 1980 – 1987 1157
Rear Side Marker 1982 – 1987 12814
1980 – 1981 12929
Rear Turn Signal 1980 – 1987 1156
Tail Light 1980 – 1987 12814
Center High Mount Stop Light 1985 – 1987 194
Trunk 1985 – 1987 DE3423
Low Beam Headlight 1984 H4656
High Beam Headlight 1984 H4651
High Beam and Low Beam Headlight 1985 – 1987 9004
Back Up Light 1984 – 1987 1156
Brake 1984 – 1987 1156
Dome Light 1985 – 1987 578
1984 6411
Front Side Marker 1984 – 1987 12256
Front Turn Signal 1984 1157
1985 – 1987 P21/5W
License Plate 1984 – 1987 T4W
Parking Light 1984 – 1987 1157
Rear Side Marker 1984 – 1987 12814
Rear Turn Signal 1984 – 1987 1156
Tail Light 1984 – 1987 12814
Center High Mount Stop Light 1985 – 1987 194
Trunk 1985 – 1987 DE3423
Low Beam Headlight 1980 – 1985 4652
1978 – 1979 H5006
High Beam Headlight 1980 – 1985 H4651
1978 – 1979 H5001
High Beam and Low Beam Headlight 1986 – 1987 9004
Back Up Light 1978 – 1979 1073
1980 – 1987 1156
Brake 1980 – 1985 1156
1978 – 1979, 1986 – 1987 1157
Dome Light 1980 – 1987 578
Front Side Marker 1980 – 1985 12256
1986 – 1987 12821
1979 1816
1978 194
Front Turn Signal 1978 – 1979 1157
1980 – 1987 P21/5W
License Plate 1978 – 1979 1816
1980 – 1987 T4W
Parking Light 1978 – 1987 1157
Rear Side Marker 1980 – 1981, 1983, 1985 12929
1978 – 1979 1816
1982, 1984 T4W
Rear Turn Signal 1978 – 1987 1156
Tail Light 1980 – 1987 12814
Center High Mount Stop Light 1986 – 1987 194
Courtesy 1986 – 1987 6418
Engine Compartment Light 1986 – 1987 12814
Glove Box 1986 – 1987 12256
Inner Tail Light 1978 – 1979 67
Outer Tail Light 1978 – 1979 1157
Trunk 1986 – 1987 DE3423
High Beam and Low Beam Headlight 1988 9004
Front Fog Light 1988 H3-55W
Back Up Light 1988 P21W
Brake 1988 1157
Dome Light 1988 578
Front Side Marker 1988 12256
Front Turn Signal 1988 P21W
License Plate 1988 T4W
Parking Light 1988 12814
Rear Turn Signal 1988 1156
Center High Mount Stop Light 1988 12961
Engine Compartment Light 1988 T4W
Glove Box 1988 12256
Inner Tail Light 1988 12821
Outer Tail Light 1988 1157
Trunk 1988 DE3423
High Beam and Low Beam Headlight 1988 9004
Front Fog Light 1988 H3-55W
Back Up Light 1988 1156
Brake 1988 1157
Dome Light 1988 578
Front Side Marker 1988 12814
Front Turn Signal 1988 P21W
License Plate 1988 T4W
Parking Light 1988 12814
Rear Turn Signal 1988 1156
Center High Mount Stop Light 1988 12961
Engine Compartment Light 1988 T4W
Glove Box 1988 12256
Inner Tail Light 1988 12821
Outer Tail Light 1988 1157
Trunk 1988 DE3423
High Beam and Low Beam Headlight 1986 – 1987 9004
Back Up Light 1986 – 1987 1156
Brake 1986 – 1987 1157
Dome Light 1986 – 1987 578
Front Side Marker 1986 – 1987 12821
Front Turn Signal 1986 – 1987 P21/5W
License Plate 1986 – 1987 T4W
Parking Light 1986 – 1987 1157
Rear Turn Signal 1986 – 1987 1156
Tail Light 1986 – 1987 12814
Center High Mount Stop Light 1986 – 1987 194
Courtesy 1986 – 1987 6418
Engine Compartment Light 1986 – 1987 12814
Glove Box 1986 – 1987 12256
Trunk 1986 – 1987 DE3423
High Beam and Low Beam Headlight 1988 9004
Front Fog Light 1988 H3-55W
Back Up Light 1988 P21W
Brake 1988 1157
Dome Light 1988 578
Front Side Marker 1988 12256
Front Turn Signal 1988 P21W
License Plate 1988 T4W
Parking Light 1988 12814
Rear Turn Signal 1988 1156
Center High Mount Stop Light 1988 12961
Engine Compartment Light 1988 T4W
Glove Box 1988 12256
Inner Tail Light 1988 12821
Outer Tail Light 1988 1157
Trunk 1988 DE3423
High Beam and Low Beam Headlight 1988 9004
Front Fog Light 1988 H3-55W
Back Up Light 1988 1156
Brake 1988 1157
Dome Light 1988 578
Front Side Marker 1988 12814
Front Turn Signal 1988 P21W
License Plate 1988 T4W
Parking Light 1988 12814
Rear Turn Signal 1988 1156
Center High Mount Stop Light 1988 12961
Engine Compartment Light 1988 T4W
Glove Box 1988 12256
Inner Tail Light 1988 12821
Outer Tail Light 1988 1157
Trunk 1988 DE3423