The Ford parts catalog also has a serial number break at V80,001 for the brake system. In the text catalog, section 11.1, page 1 shows, in the application section it breaks it down as:
F250 2WD w/ HD brakes-dual piston '73-'75 before s/n V80,001 use parts list 31, '75/ from s/n V80,001 use parts list 235.
To the OP, with your s/n (X03237) you want to use the from s/n V80,001 parts.
Just a note: The only differences the s/n makes is for the heavy duty dual piston caliper brakes. According to the parts catalog, there isn't any differences in the standard duty single piston caliper brakes. All years 73-79 use the same parts list 26.