I would recommend nissan plugs Part #22401-FU42A they are an updated plug that has the first three threads removed as they had issues with the old plugs coming out of the head hard and taking the threads out with the plug,be VERY careful when changing plugs,do it with the engine cold and work them out easy.
I guess the threads on the old plugs get carbon build up on them and are a bear to get out of the head with out damaging the threads,especially on high hour trucks.