Extra holes in coupe/roadster rear bumper arms

[wrndln]

It has been brought to my attention that some 28/29 coupe/roadsters have two extra holes in the rear bumper arms (see picture - the one with my hand on it). The extra holes are on the inner side of the standoff. My 28 special coupe does not have the extra holes in them, only the 3 holes for the cross bracket. I have a pair of rear bumper arms I bought at a swap meet, so I don't know what year the arms came from, but they have the extra holes. I suspect 1928 coupe/roadster arms don't have the extra holes and for some reason (trunk rack maybe), Ford punched the two additional holes in 29 arms. I am only guessing that 29's had the extra holes and what they may have been used for. If you know if only 29's had extra holes and what they were used for, please post a response. The holes appear to be factory punched and not drilled by someone after leaving the factory.
Rusty Nelson