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The relay assemblies are quite different. The 600 has a 13-pin unit that incorporates the fuel pump relay, the starter cut-off relay, the safety interlock diodes, and a resistor to test the oil level warning lamp. It has a separate turn signal flasher with cancelling circuit. The 400 has a separate fuel pump relay, separate diode block, and a 9-pin 'flasher relay' (with cancelling circuit) that incorporates the starter cut-off relay. It also has a separate side-stand relay (Normally-open).