If a part is temporarily unavailable, you could substitute it with these parts:
Quality Differential parts for Smart FORTWO electric drive / EQ 56 hp Electric
Wide selection of new differential parts for Smart Fortwo 3 Convertible electric drive / EQ (453.491) Electric 56 hp, priced from £2.24 to £33.07. Choose from 6 trusted manufacturers.
Differential parts for SMART FORTWO models
1.0 (451.331, 451.380) M 132.910
0.7 (450.352, 450.332) M 160.920
0.8 CDi (451.300) OM 660.950
1.0 (451.330, 451.334) M 132.910
0.8 CDi (451.301) OM 660.951
1.0 Turbo (451.332) M 132.930
1.0 (451.431, 451.480) M 132.910
0.8 CDI (450.300, 450.301, 450.302, 450.303, 450.306) OM 660.940
1.0 (453.342, 453.343) M 281.920
0.7 (450.452) M 160.920