For the tanks, crawl underneath and if you can see the tanks, you can get a model number and look them up. My 27DBK Salem has 3 tanks, galley, grey and black. It was advertised as if they were different capacities, but they're all the same tank, coming in at 33 gals each.
2018 Salem 27DBK
2004 Ram Quad 1500
Days past:1996 Coachman Capri-Ruby Ed. 27DS
1995 GMC Yukon Sport
Days Camped:'13-10 '14-20 '15-6 '16-9 '17-14 '18-3