Maybe someone can help me with this. An older subpanel was converted to more of a junction box. Is this acceptable? Right now I’m only recommending closing the unused openings in the panel where breakers were installed at one time.
It is an acceptable practice. I would comment on the rust and also recommend closing the holes.
I agree with Taylor
It is acceptable and you are correct with your call.
But it’s an FPE Stablok! Replace it now. :mrgreen:
Actually it is just a junction box. Close the openings. Many times the cover is just screwed shut. 
I wouldn’t even mention the rust. I would simply suggest securing the cover.
Aren’t the openings are closed when the cover is shut? Just wondering, can’t a junction box have a hinged cover?
Troughs can have a hinged cover.
Duct tape is dirt cheap!!
It can be used to repair torn screens, holes in the fender of your car, hold broken lawn chair frames together, fix plumbing leaks, secure the deadfront closed,and cover holes where breakers used to be! 