When doing replacement or upgrading on 1977 – 1989 Dodge Diplomat, the bulb size guide is necessary for you to take the reference.
Jump to corresponding car model with the catalog bellow.

Low Beam Headlight 1977 – 1989 H4656
High Beam Headlight 1977 – 1989 H4651
Back Up Light 1977 – 1989 1156
Brake 1977 – 1989 1157
Dome Light 1977 – 1978 211-2
1979 – 1980, 1982, 1984 – 1989 578
1981, 1983 912
Front Side Marker 1977 – 1989 168
Front Turn Signal 1977 – 1981 1157
1982 – 1984 2057
License Plate 1977 – 1989 168
Parking Light 1977 – 1979 1157
1980 – 1983, 1985 – 1989 194
1984 2057NA
Rear Side Marker 1983 – 1984 1157
1977 – 1979, 1982 168
1980 – 1981, 1985 – 1989 194
Rear Turn Signal 1977 – 1989 1157
Tail Light 1977 – 1989 1157
Front Inner Turn Signal 1985 – 1989 2057NA
Front Outer Turn Signal 1985 – 1989 194NA
Center High Mount Stop Light 1986 1156
1987 – 1989 921
Courtesy 1979 – 1981 161
1984 212-2
1977 – 1978, 1982 – 1983, 1985 – 1989 90
Engine Compartment Light 1977 – 1978, 1981 – 1985 1003
1986 – 1989 105
Glove Box 1980 – 1989 1891
1977 – 1979 1893
Map Light 1977 – 1980 562
1981 – 1989 912
Radio Display 1980 – 1983 158
1977 – 1979 194
1984 – 1989 74
Trunk 1977 – 1985 1003
1986 – 1989 105