a/c compressor leaking at line connections

I am having trouble with the A/C compressor on my 1984 300D.
It appears that there were several hose-block connections and compressor connection configurations.
I ordered a new compressor (for a different car). It came with the adapters and instructions. Unfortunelty, I'm having trouble understanding them.
I can't get the compressor to stop leaking at the hose connections in the rear.
I have ordered new o-rings in the past, and they have sent me 2 different types. One set was simply nitrile o-ring, the other kind were metal washers with o-ring attached to ID of the metal disc.

Thanks for any help you can give.

Cory

W123