Oscilloscope connector

The inputs for the oscilloscope are regular BNC connectors, but the ground connector is one I’m not familiar with. It looks kind of banana plug-ish, but longer than what I’d normally expect for a banana plug.
Here’s the ground connector on the scope
There’s also this BNC adapter for some other kind of plug. Looks kind of like a phono connector.
I was able to find a manual and service manual for the scope, which will come in handy.
Next step will be to plug it in and see how things are.