Just to update this thread....
Finding rebuildable cores is becoming very very hard and has been for most of 2015. So I don't really offer these rebuilt units on any consistent basis. If I have one I normally sell them local within a day or two.
The best option IMO is just to buy a new T56 Magnum from me if it's in your budget.
Finding a used trans that is 15 years old means it typically needs a rebuild. Once you do that... you aren't far away from a new T56 Magnum that shifts smoother, holds more power, is simply a better transmission in every respect. A rebuilt '93-06 T56 will never shift as nice as a T56 Magnum (TR6060).