When doing replacement or upgrading on 1975 – 1978 Fiat 131, the bulb size guide is necessary for you to take the reference.
Jump to corresponding car model with the catalog bellow.

Low Beam Headlight1975 – 1978 H5006
High Beam Headlight1975 – 1978 H5001
Back Up Light1975 – 1978 1156
Brake1975 – 1977 1156
1978 1157
Front Side Marker1975 – 1978 194
Front Turn Signal1975 – 1978 1157
License Plate1976 – 1978 97
Parking Light1975 – 1978 1157
Rear Side Marker1975 – 1978 194
Rear Turn Signal1975 – 1978 1156
Tail Light1978 1157
1975 – 1977 97