I won mine at the 2006 Fall Rally.
I know that CW doesn't carry them in stock but I believe you can order them.
It is a Valterra T50 Assembly
The photo I used came from Sun Country Services
I also found it listed at rvparts4u.com
I have no good or bad information on Sun Country or rvparts4u.
This valve attaches with a 1/4 turn twist just like your sewer hose attaches. I do not suggest cutting the sewer pipe or gluing.
Use a Hose Clamp where it connects to the Montys sewer pipe and forget it. As I said, I won mine in 2006, installed it the next day and it works just like new 3 years later.