[goinbig]

The t-case is connected to the back of the tranny. If it is in 4wd, the front drive line has to spin if the rear shaft is spinning.

The problem sound to be in the manual engage you made for the front. The thing you made/installed is not a locker or anything either. It simply eliminates the vaccuum actuator (witch you no longer need). It makes it so that you can have low-range 2wd.

Sounds like you should get down there and look at it. If you put it in 4wd, and only the rear has power, it is because of that actuator...not the shifter linkage (which you might have a problem with, but that's another issue).