What goes between the gate valve and the termination cap?

[Straylight]

I'm replacing a bunch of rusted-out or melted bits on my black/grey water drainage system, and I can't figure out what I need at the sewer terminal. Right now there's a 3" gate valve and a termination cap, but it doesn't look like those two parts fit right together without anything in between---and it doesn't look like I'll be able to hook a sewer hose directly to the gate valve when the cap is off. Unfortunately, the old sewer terminal is borked beyond repair, so I can't disassemble it and figure out what's going on; I need to rebuild from scratch.

What am I missing here? Is this just a part that people don't need very often (and is thus hard to find), or am I an idiot? Happy to admit to the second possibility at this point

[eric1514]

What you linked is a 1.5" gate valve. Make sure you order what you really want.

Then you'll need to glue on a termination adaptor to the valve or to the end of the plumbing you construct that exits at the curb. That termination cap will then twist on.

Eric