The sizes should be the same, you'll just need 4 more for the bed-I'm not sure on the '10 if just the front bolts are shorter, so you might want to get a couple of extras just to be safe.
Drilling-out the core support bushings is 1) like a 5 minute job, 2) you'll likely destroy the threads when you're walking the OE bolts out, and 3) because of the way that the truck is built on an assembly line, those bushings are apperently threaded onto the core support bolts long before the cab ever meets-up with the chassis, at which point the nuts are installed (or vice-versa-it's been over a year since I did mine). Long story-drill them out.
Just trim the shroud with a Dremel-go a little ats a time, checking for clearance as you go.
'04 XLT SuperCab--4x4--4.0 Cammer--Auto--4.10 L/S--Leather Sport Buckets--OEM Pioneer 290W System--Billet Grille in FX4 Surround--aFe Magnum Force Intake--Bassani Lightning-style Exhaust--SCT X-Calibrator 2--Black Headlights & Corners--Extang FullTilt Tonneau--Herculiner--Cranked "1" Code Torsion Bars--NS'd '06 Tails--RS9000s--16"x8" Mickey Thompson Classic Locks with Blue Trim Rings--265-75R16 REVO2s--1" Body Lift-----SOLD
New Ride:2014 Focus ST