Vintage API module screws?

[Golgoth]

I am looking for a bunch of these tiny screws used to tie vintage API modules chassis.
They are very short, not like the ones used for the cover on the top and in the back.

Does anyone know the thread / reference I need? I don't have rulers or calipers at the moment and would like to order the right ones..

Thanks!

 

[David Kulka]

3-48 I think, or possibly 2-56.