[Randy in ca]

Another way to tell them apart at a glance is to check the flange where the bracket bolts to the frame:

On the 1928-29's the flange is much thicker at the lower bolt hole than it is for the 2 upper bolts. As well, the lower uses a 1/2" bolt while the 2 upper ones are 3/8".

The 1930 brackets have the thinner flange uniform for all 3 holes and use all 3/8" bolts to attach.