Missing Plumbing

All,

I am looking to re-instate my sewer connections. Bought the RV from a fire department. They used as a demo vehicle for safety. They disconnected the plumbing.I do have the sink hooked up tho. So the grey water does flow as it should thru the T shutoff pipe shown.

What do I need to buy to get it in working order? That is - exterior wise for now. I will deal with toilet side later. I know I need a "y" connection of some sort - but don't know what all is involved.

You can see from pic 1 that they removed stuff and covered with wood and screws. The grey water connection works fine. But I am sure something connects to that. In pic 2 it shows wood removed and some small debris in side. In pic 3 is a piece if what looks like a ring that was removed. It was just sitting in the hole with debris. No idea why they just left that? In pic 4 it shows a metal hanger for a good size pipe or hose.

I tried to look online but am confused as to what I really need.

Help?

Thanks,

Wayne

:@