Very much appreciate the responses.
gbopp, I haven't been able to figure out how to get it apart. The gray "cap" has a surfaces that would seem to allow a wrench to unscrew it, doesn't budge, material of gray cap has some give, doesn't allow wrench to hold on. I've tried prying the gray cap material off, no luck.
ronfisherman, disappointing to hear, was going to call Valterra on Monday.
Chris Bryant, definitely will look into the Watts if I can't get the leak in this one fixed.
Thanks everyone!
2013 Silverado 3500HD - Duramax/Allison - CC, long bed, SRW, 2WD
2017 Grand Design Reflection 303RLS - TST 507 TPMS