Anything is possible in the land world. Somewhere on here somone did it. It looks crap, it looks bodged! It must feel ****e to drive with the gear leaver in the middle seat it was shocking! Sometimes there is a right way and well lets be honest lots of bodges.
Defender has long stick (gear stick in front, tranny leaver behind) Just to add to the equasion Bell housing input shafts can be different lengths too:
i.e an early 90 2.5/2.5Td all had a short bellhousing whereas defenders from 200tdi have long type bellhousing same as disco's that is why the engine in a 200tdi defender is 100mm furthur forward to a 2.5na or 2.5Td.
Disco have short stick Tranny leaver in front gear leaver behind) and a long bellhousing
IF its possible and I heared somewhere that it was you could fit the long stick top housing to the disco box if the bell housing was suitable for your application. i.e the same as alreadyt fitted.
hope this helps,
Jai