AFE 4" Air Filter
Features & Details:
This is our suggested intake system for 7.3 diesel trucks. It will need a 4" piece of tubing made to attach to your OEM intake sleeve and that is all. 

4" x 8.5" air filter fits 7.3 Powerstroke trucks rated at 850CFM. Washable 5-layer cotton filter with progressive layering media will flow at high levels even when dirty.
AFE 24-91042