So few posts, so much confusion.

If you're changing the box to the 2.0's MTX75 then it's a massive job, you'll need just about everything from the 2.0's engine bay. If you keep the IB5 then it's very straight forward...you just do what I said above.

1.8 and 2.0 driveshafts aren't the same, the splines are different.