wfederle, welcome again your black tank will be 50 gal,gray 50 gal, fresh water two 40 gal tanks split between chassis rails, connected by 1 1/2 inch tubing. If you look closely you may find a stamping on side of tanks. Please post your coach info in your sig-profile it will be easier for you and us. Don't you have the Ford V-10 engine? If you posted your questions on the Newmar forum below you will be contacting the Newmar owners everyone does jump around tho. You can also become a member of Newmar forum free of charge.