'47, & '48 GMC 1/2 ton thru 1 ton trucks use the bumper bar style grille, like the 1 1/2 ton, & up trucks use. This bumper bar grille, is braced to the frame, & has 3 cross bars, instead of 4 cross bars. The '49 thru '55 1st series grille, mounts differently. I'm not saying it won't work, but I am saying it won't be a simple bolt, for bolt swap.