SOURCE

Nissan Original Part Number: 21082-Y4101.
Cheapest Compatible Part Number from Nissan: 21082-Y4161
GMB Part Number: GWN-33F.

Replacement is simple and does not take more than half an hour with proper skill.

1. First, remove the plastic air intake cover which is attached by three screws.
2. Remove the upper part of the fan housing: two bolts using a 10mm wrench, be careful not to break the clips on the lower part of the housing.
3. Unscrew four nuts holding the viscous coupling and fan in place with a 10mm box-end wrench.

4. Take out the viscous coupling, unscrew the fan from it — held by four bolts.

5. Reassemble everything with the new viscous coupling in reverse order.