If its a lock up 904, its likely a 998 or 999. ITs a lock up because it allows the TC to lock up. The input shaft has a passage through the center that allows this function, as well as valving in the VB to operate it. You'll need a new input shaft and a VB. I do not recall if the cases are interchangable. It may simply be easier to find a non lockup 904 and use it.
