Isomorphic classification problem and linear topological invariants

We consider all possible isomorphisms of cartesian products of Dragilev spaces, and thanks to relations between the Dragilev functions of each factor try to show that if there exists such an isomorphism, then any factor on the left of the isomorphism is nearly isomorphic to the corresponding factor on the right. We also try to get a liecessary condition for the isomorphisms of the tensor products of infinite type Dragilev spaces by the dual of an infinite type Montel power series space.