The late Volvo 5 blade asymmetric fan is supposed to be a bit more efficient and run a little quieter. They are plastic rather than metal. Not sure if they were fitted as stock to any model? Not cheap and I would say that they aren't a cure all for cooling problems. A rad that needs at least a good flush or a recore a more likely cause or a poor water pump. Pattern pumps with pressed steel blades can be poor. A genuine Volvo bypass type thermostat also recommended.