Need size of caplug in spare tire well

[SwingerDeluxe]

I have the smaller of the two body plugs missing in my spare tire well. The larger one is a Caplugs 2 1/2". Does anyone know the size of the smaller one closer to the back of the trunk? I will order from Caplugs if I know the size. Thank You Much!

 

[SwingerDeluxe]

I forgot to note that this is on a 72 Dart.