Shift tower mystries?

[BEAR WABBIT]

I recently broke the casting on the bottom of the tranny which houses the support bushing and have to replace the back portion of the transmission /shifting tower.
I have the "car disk" and therefor the picture of what the tower looks like inside but am still worried about taking it apart as I can already see a spring in ther that is not on the diagram. The tranny is out of the car and on the bench so is easy to work on.
I just need more confidence about how to proceed and what I will find inside the tower before I proceed.
Any help would be greatly appreciated.
thanks
jim