Totally wrong.
Just read the TSB. The factory themselves gave the information, not me. November ish '72, so a few months into the '73 model year, the 10" drum brakes went to a B-body style drum. Those drums used the larger '73+ wheel bearings AND the larger upper ball joints. The 5x4" pattern was retained on ALL drum/drum cars until the middle of the '76 model year, there were never any A-bodies with front drums with the 5x4.5" pattern. From 73+ only /6 cars came with 4 wheel drums, the v8 cars came with the 73+ disks and had the larger 5x4.5" pattern.
So, 73+ /6 car with front drums = 5x4", 73+ V8 car with front disks = 5x4.5". And some /6 cars got front disks too, they were an option and some packages (like towing, or a rear sure grip) would add front disks too.
The OP's '74 will have large ball joints and the small bolt pattern. They should look like this and have the same casting number
[SOLD] - 1973-76 10" Drum Brake Spindles (LBJ) 3402738
View attachment 1715922910
The picture is from
@cudak888 's recent sale thread.
Or cleaned up from
@67Dart440GT [SOLD] - 10 inch front spindles
View attachment 1715922908
or maybe
@moparmat2000 or
@BergmanAutoCraft can comment about the later drum spindles having the LBJ from their thread
[WANTED] - 73 -76 A BODY DRUM SPINDLES
The 73+ drum spindles were pretty sought after for awhile because of the LBJ and because there were several aftermarket brake upgrades that only worked with the 73+ A-body spindles, particularly a Viper front brake kit from
@DoctorDiff
