Depends on the engine!
Just replaced the 2.7TDi engine from my 1998 Terrano.
You also need to remove the gearbox, it isn't possible to remove the engine without that because of the oil pan. This because there isn't enough room tot get the engine free from the gearbox.
You can get problems with the NATS (Nissan Anti Theft System). I had the problem that NATS didn't want to turn on the fuelpomp because of the engine replacement because the computercode's don't match anymore.
Sander
October 2008