Originally Posted by coairstream
I take it I should have the tank fabricated around the beams? Any recommendations on were to get the tank?
Your black water tank, sits between the main frame.
There are several appraoches to where to install a gray tank.
Generally speaking, it should be near the rear axle.
Or, if you change out the black tank, to a later model, you can have the black and gray tank, next to each other, and both going front to back, or, within the frame, one forward of the other, as in the later models.
Decide what you want to do, and come up with dimensions, "BEFORE YOU DO ANYTHING." That will save you some measure of grief.
Once you have the dimensions, then you can shop around, for the tank or tanks.
Depending on whast you come up with, the tanks may still be available from Airstream. If not, then you will have to chase down a source, or locate someone that may have reproductions that match the sizes you need.
More than likely, you will wind up with after market tanks, that are made by tank manufacturers.
Use caution, with your design.