Gas Gauge Inner Nut

[Bill in SoCal]

The picture is of the gas gauge from my early 30 coupe. Notice the inner nut. The standard tools I have do not fit. They fit a 5/8 opening. Mine has a 21/32 opening for the tool. The lens in the middle is smaller and does not appear to have a face plate behind it. I looked in the judging standards and did not find it mentioned (maybe I was speed reading).

I am curious about this nut. What can you guys tell me about it? Bill