What's misleading is your original response said nothing about case mods. You came back and mentioned it later.
You can turn a non-lockup trans in to a lock up - need the valve body, input shaft and corresponding rear clutch retainer, pump support (reaction shaft support). There are two basic valve bodies - hydraulic control only for lockup then electronic control lockup. Early lockup control with electronics was called PTU (part throttle unlock), was one wire to actuate the lockup solenoid. You just need to be careful that you identify and get all the correct parts to do the swap.
