IF you are going to use the DI Shifter, you should get the hi/lo selector housing from the DI and put it on the D2. It is bolted by 6 bolts on top of the front out put housing. Below you see where the DI housing on the left is and the D2 03' housing on the right is. (It has been removed and this is to reference location)

Notice the difference in the shape of the lever on a DI "S" Shape lever. (you can see the housing that i mentioned from above and the lever that sticks out from it)

and

Compared to a D2 straight lever.

If you DONT get the "s" shape style housing to swap, then you would have to bend and reshape the DI shifter to fit and work with the D2 Lever. It is possible but I hear it isn't fun to do. if you can get the DI housing the swap and function will be smooth!

This setup did NOT use the DI housing on his D2 and you can see the bend required to work.