I have the seaflo from Amazon. I put an end on it with a cig lighter type plug that matches the jack I put in my 5er.
for outlet I went to Tractor supply and found a plastic fitting that matches garden hose, and a short piece of 1" clear hose, 2 clamps.
I use it all the time.
I first empty black tank.
Turn pump off (which stops any flow)
leave black valve open, and open gray valve. This allows water to back flow into black tank (you can hear it moving).
Shut off gray valve, and turn pump on.
I keep doing this until I am out of gray water.
I use a (brown) 5/8" garden hose. just make sure you always coil it up correct so the hose don't get kinks in it.
My first pump went bad after 3 years. front sealed bearing went bad (still works, but leaks). First pump is a different brand, but looks exactly like the sea flo. tempted to buy the new bearing plate (bearing is staked into plate) and put it on my old pump as a spare.