[Wheelhouse]

When my black water valve started leaking, I cut the 1/2” plywood above it in the storage bay above it. Cut the plywood shallow so you do not cut metal brace and ruin blade. Do nit be afraid of cutting plywood. I had to cut plywood access one metal brace.
After exposing the valve, I cut 1/4”-1/2” off the discharge side of valve. Remove the gate valve.
Measure the discharge side black pipe.
Now go to supply hose and get Rubber slip coupling and slide on discharge pipe.
Install new gate valve. Leaving the gate valve off while placing the rubber coupling is easiest.
Now replace cut out plywood and you are done.
I can send pictures if requested.