2018 Solitude 373fb Tanks and Sizes

[KennethWood55]

We just purchased a used Solitude 373fb and dealer told us that there was one gray tank and one black tank. However, there in monitoring for (2) Gray and (2) Black on the control panel. The dealer told us that they use the same monitoring panel for trailers with single and double tanks. The specs for this trailer say (1) 100 gallon gray and (1) 50 gallon black.
On our first outing I found the monitor showing different levels for each gray tank and each black tank? Then when we went to dump the tanks I found a second set of valve handles tucked up under the frame near the sewer dump and a second black tank flush mounted to the outside of the trailer above the axles.
We definitely dumped (2) black holding tanks and (2) gray tanks and the monitoring supported that. So anyone know what the tank sizes are? I'm guessing (2) 50 gallon Gray and (2) 50 gallon black? But that's not what the spec sheet from grand design says or the dealer?
Anyone else experience this?

[Darkmoon]

Hi Kenneth. We just bought a 2019 373FB and had a similar experience. Nowhere can I find the size of the tanks. Supposedly Grey and Black water capacity is 100 gallons total. My dealer did share the two black tanks (and showed us the second black valve and assured all were closed on delivery) but only mentioned one grey tank. Much to my surprise when I took the sewer cap off and was greeted by a blast of grey water (thankfully not black!) even though I "knew" the grey tank valve was closed. Kind of a shock figuring out where the grey water was coming from and if we had some kind of valve leak. Sure enough there was a second grey valve next to the front black valve and it had been left open by the dealer. I'm assuming the same as you, 50 gallons each on each tank.

[KennethWood55]

Thank you for your reply Darkmoon. We’ve gotten a chance to use our trailer a few times since I posted the question and hope you enjoy your 373FB as much as we do. I haven’t measured each tank, but I’m almost certain that there are 2-50 gallon grey tanks and 2-50 gallon black tanks under our trailer. Makes it kind of nice to have the extra capacity that you didn’t know came with the trailer...