Your pic shows that the core is 1 1/2" in from the edge, so assuming that the other side is the same your core is probably 29" wide. Our page at Documentation/Cooling Systems/Shroud Part #'s there are two that come pretty close to that - one for the 300 six and one for the 460. But they differ in height and bolt hole spacing.
So, where I you I'd go to that page and compare the dimensions to your radiator's height, width, and bolt hole spacing and pick the one that comes closest to matching.
Gary, AKA "Gary fellow":
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Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI