We have a CrossTerrain, TF32SS, 32' triple axle toy hauler. We have a grey tank, a galley, a black tank, and two freshwater tanks. Also a fuel cell.
Unless you have two toilets, I would only expect one black tank. I've never heard of a non commercial rv with two black tanks about your length.
The black tank covers the toilet only. The grey tank comes from the bath lav and the shower. The galley comes from the kitchen only and has a separate pull tab over the exit plumbing.
Our gauge center has two sensor panels to check for both freshwater tanks and two sets of batteries, however, there are only one set of batteries, that measure off both gauges. You may have two black tank indicators when really you don't?
Hope this helps.
Bob and Better Half
2007 F-250 PSD, SW, CC, LB, 2WD
2006 TF32SS Cross Terrain Toy Hauler (sold)
Reese 16k slider