I have a 2000 JTD 110 ELX gearbox taking up space at home, it's done around 140,000 miles. We swapped the engine and gearbox complete from a scrap car to my Multipla when the engine failed and I kept the original box.
I'm not sure about the condition of the box but it did make it to France and back not long before the car was laid up for a few years and can't remember any problems when I drove it.
Maybe someone could look over it before fitting or you could make one good box from two??