50+ Richmond gas furnace exhaust?

Hello Everyone…I’ll try to describe this as best I can. Inspected a 56yr old cape today and came across an original heater. It was a richmond gas furnace that actually looked to be in good condition. My question is if you look to the right of the water heater(Black box) this is where the exhaust enter the chimney.

  1. 90 deg angle and the bottom of the black box has no cover?

It looks like there has never been a cover on the bottom of the black box? Is this installation correct. Similar to a oil furnace is this to dilute or cool down air from furnace when it enters chimney. My concern is back drafting and exhaust entering the home. Has anyone inspected a furnace like this? It was a monster 2x4 foot long!

Any info would be helpful…