Which spark,plug for 2004 8.1s 340da

[sporters78]

Ac or ngk or champions ? Part numbers ? Time for me to change them out. I have 4 ngk..prg5a-11 laying around , last time I put in ac delco, what's good and long lasting? And where to buy? Any difference between auto and marine plugs( stainless steal)
thanks

 

[Kreole Kid]

http://clubsearay.com/showthread.php/26439-How-Why-to-Change-Spark-Plugs-in-8-1-s

 

[Kreole Kid]

http://clubsearay.com/showthread.php/62368-Changing-spark-plugs