I always carry some extra fuses just in case one fails, although since I switched the Pantera over to a modern fuse box with ATO type fuses, that hasn't happened. Depending on what type of fan relays you are using a spare relay might not be a bad idea to have. Of course there is always some wire and electrical connectors just in case you have to jumper a failed radiator fan coolant temperature sending unit. Yes those sending units can and do fail. Been there and done that before!