Looks like HD modified the spacing of the holes from then till now. I just pulled the right side bracket off and tried to seat the rear bolt in the lower hole - there are 3 holes, with the bottom 2 being threaded. However, the bracket has a stub that fits into the top hole, and the spacing between the bottom two holes prevents me from using the bottom hole.

I guess I could either file that stubby post off, or use a 1/4" spacer for that bottom hole. I didn't look at the left side yet.

 

That stub is there for a reason. It is a locking pin to prevent rotation.