64 Dart GT Gas Tank Help

I am about to replace the tank in my 64 dart and I am confused about the grommet.

I measured the fill tube and it looks like it is 1 3/4 just like my 63 dart ?

should I order a 63 tank ? I know a 2" grommet is going to be too big and the 63 tank comes with a 1 3/4 grommet.