Kin ell, changing a 2.6V6 into a 2.5TD auto is going to be a challenge!
So it appears, the worse bit appears to be the wiring, although investigating the looms so far it appears that the V6 harness is far more complicated than the TD one; as I have a U25TD there is no MAF sensor to worry about to start with. I certainly am not expecting plug and play, but I don't envisage too many problems, after all I have a complete doner car to play with. I expect that getting issues like getting the trip computer display to talk to the ECU and the climate control to work correctly. Traction Control might be a complete mare, but who needs that ?? Getting the engine in and running should be straight forward (ish) though.
I agree that the AR25 will be fine and I have one of those attached to the V6, hence the real need for a bellhousing and TC to fit the AR25 to the TD engine and that can come with a knackered autobox for all i care
I'll post pictures of the fun if you like in the "Gallery"