What is the difference between the 3d stuff in DelphiX and the way 3d is done using DirectX 8.1 or 9?

Would it be feasible to take 3d programs made using DelphiX and "upgrade" them to DirectX 8.1?

The reason for the question is that I would like to be able to use animated .x files. I have DelphiX programs that do this using retained mode but I don't want to learn methods that aren't used anymore.