spud your in luck mate because the mechanic is talking rubbish. My CA18DET ute was engineered in NSW originally (I can get the engineers name if you would like me to send it to you). My ute was originally engineered with the drum brake rear end and Mitsubishi Verada discs with Commodore calipers up front.

When it came to getting the ute re-registered in the ACT I had the whole thing re-engineered with a borg warner diff and VN V8 rear discs and calipers. The new certificate also includes the EMS computer, FMIC, BOV, boost controller and ram pod though you may have some trouble getting these on a NSW certificate.

As Chris said ring up an engineer and follow his guidelines. The reason you get a car engineered is so you know that the car is safe.

Just as a side note, you are able to get an SR20DET 1200 ute engineered in the ACT (not NSW). I know this because we have checked it out with our local engineer and he has already done one we just have to follow his guidelines.

Cheers