I did a deep dive look online and find ZERO links for parts for this. It is a Kwikee product and it was purchased, of course, by Lippert (LCI). I did find a thread on IRV2 from 2017 for someone looking for that part.
Here's a link
https://www.irv2.com/forums/f54/leve...ap-364720.html but every single link in the thread is dead or missing.
If it screws in, and leaks, perhaps some plumber's Teflon tape would do the trick?
You might call Lippert Customer Care:
Monday - Friday: 8AM - 7PM (ET)
432-LIPPERT (432-547-7378)