When doing replacement or upgrading on 1989 – 1994 Audi 100, 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 1989 – 1994 9004
Front Fog Light 1989 – 1994 H3-55W
Back Up Light 1989 – 1994 1156
Brake 1989 – 1994 1157
Dome Light 1989 – 1994 578
Front Side Marker 1989 – 1994 12821
Front Turn Signal 1989 – 1994 P21/5W
License Plate 1989 – 1994 T4W
Parking Light 1989 – 1994 1157
Rear Side Marker 1989 – 1994 12821
Rear Turn Signal 1989 – 1994 1156
Tail Light 1989 – 1994 1157
Center High Mount Stop Light 1989 – 1994 12505
Courtesy 1989 – 1994 12256
Engine Compartment Light 1989 – 1994 578
Glove Box 1989 – 1994 12929
Stepwell 1989 – 1994 12844
Trunk 1989 – 1994 6411