Pictured above is a comparison between the typical 1930-31 Model A headlamp mounting bar (A-13114 Headlamp Tie Rod and Support Assembly) on top and the 1932 Model BB truck and commercial headlamp mounting bar (BB-13114) on the bottom.
Not shown are the 1932 passenger headlamp mounting bars. The 1932 Model B passenger bar had a wrapped polished stainless steel skin over the bar section between the lamps. The Model 18 V8 headlamp mounting bar was the same as the Model B except it also had a vertical hole through the center of the bar for mounting the V8 emblem.
The pic above shows the relative similarity between the Model A headlamp mounting bar on top and the 1932 Model BB truck and commercial bar on the bottom.
Also note that the Model A headlamp mounting bar has a squared-off boss under the headlamp mounting hole whereas the 1932 bar has a simple round shape around the hole.
The squared-off boss fits the Model A horn mounting bracket and keeps the horn from rotating. The 1932 horn is mounted on the fender frame shelf and is not attached to the headlamp mounting bar.
The pic above shows the forward sweep of the 1932 bar on the bottom which bows forward to clear the protruding 1932 radiator grille. The Model A headlamp mounting bar on top is more or less a straight line from fender to fender.
The pic above also illustrates the square shape of the mounting holes in the Model A bar on top which uses the square shank carriage style bolts. The 1932 Model BB truck and commercial bar on the bottom has oblong slotted holes oriented fore/aft, and uses the special 1932 style oblong shank carriage bolts.
The pic shows the special 1932 style oblong shank carriage bolts used for mounting the headlamp bar. Also note that the bolt head is not perpendicular to the bolt shank itself, but is canted to match the fender and lamp bar shape.