Ok, my 26RD apparently has 2 gray tanks. 2 dump levers and 2 indicators on the panel.
My question is what drains to what and what are the capacities.
Well, it would appear your capacity question has been answered by Socal-Paul. I believe this should also be documented on the Alliance Rv site under the specifications for a given model.
As far as what drains into each tank, that could be a mystery😀.
I would suggest you empty each gray tank, place a bucket under your discharge, open one gray lever and run a faucet to see if water comes out your discharge, repeat the steps for each faucet/drain and tank. This way you know for sure which faucet drains into which tank.
We did the same validation checks on our 310 RL to ensure we knew what was draining where and also to ensure that the tank level gauges were indicating a level rise in the same tank.