Gray and black tank help

[Michellh]

I recently posted about aour used Glendale 5yh wheel we just purchased and the trouble we were having locating the gray tal valve. We only see tthe black. We looked againtoday and even took the bottom cover paeky off underneath the .4th wheel. Still no gray drain. We only see one valve that
Says black. But it appears thereby have been sw
Work done to the pipes. Is it possible the previous owner could of combined both into one drain? We bieve the
Camperwy have been set up as long term and noticed frequently. If this is possible what should we
Be aware of when opening the drain to dump? We also are set up permanent and have septic hookup. Thank you!