The lt77 and R380 are interchangeable between Discos or between Defenders.
The Defender has a shorter input side, more compact clutch etc to keep the weight forwards.
Then the TDi has a shorter bellhousing than a V8
You could put the Defender one in but you'll find it sits much closer to the engine, the gearsticks will be wrong as will the propshafts and crossmemeber.
If they were both LT77 you could possibly build one box out of the two.
A mate has a 200TDi engine and box in a RRC, the engine is so far back there's no heater.
