Go outside and look where the gravity feed port is for filling, it will be close to that on the inside, most likely under the bench seats or bed on the driver side of the trailer. Then look under the trailer for the drain valve.
Ok my oven is over my tank I have a drawer. I looked there but I don't see anything under the trailer. In other ideas would help. Thank you for the reply.
Sent you a PM. Also, try calling NuWa (Kansas RV Center) in Chanute, KS. They made it and Darryl Dennis, who was there when they were being made, now owns it. Their number is (800) 835-0676. He will want the last seven of the VIN. He can tell you where to look for it.
Have you crawled under the trailer yet. Easiest way to find it. On our HH the fresh water tank was just rear of the rear axle. A black pipe was hanging down. If you slide your hand up it there was a valve. If you turn the valve and it does not drain there's a good chance a mud dauber built a nest up in it. I used a bamboo screwer to poke around and get it running. Once it starts your good to go.