if your brake drum is 14 inches across on the inside order the 1 ton brakes
however to me it looks like someone just put in longer studs into a stock 3/4 ton axle

the brake cylinder in the photo looks like it is part 5450071 which is unique to the 3/4 ton in from 1946 to 1952
the 1 ton brake cylinder has larger solid cast gears on each end and those pads don't look like they would span 14 inches face to face to fit the 1 ton drum

the 3/4 ton rear brake shoe is the same part as the 1 ton front shoe
the filling station shows they have them in stock, part number 3681116

-s