If you're a sheet metal artiste, you can make a cone-shaped shroud that covers as much of the radiator as possible and has a hole with about 3/4" of clearance from the fan blade tips. Too close, and you'll get some contact under high torque pulls from motor mount deflection- - - -trailer towing, steep hills with a full load in the bed, etc. If you're doing the "Cowboy Cadillac" thing and only hauling an iced-down Yeti cooler to the show and shine, you can get away with a bit closer clearance. Make the shroud from stainless steel or polished aluminum for the people who like the under hood area to look fancy, or flat black paint otherwise.

I prefer to just fab up a rectangular box that bolts to the core support with a hole for the fan. Either way, it helps the radiator pull all the air volume it can through the core.
Jerry

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