The original equipment air box is better than most aftermarket, you really have to pulling a lot of HP to need a different one, the diesel coolant filter probably isn''t a bad idea although the 6.4 doesn't have near the issues the 6.0 did with sand and what not.
My name is Jeff BUT "My Buddies call me Bubba"
2008 F250 KR 6.4, 2WD
1999 E250 5.4 High Top
1989 Thunderbird SC
1965 Olds 442 X2