Uteman, pretty sure that you'll have no problems dashwise, but as far as the rest of the wiring loom goes, I'm not 100% sure.
Have a look around your alternator, and see if you can find a (blue I think) wire with a plastic plug. This will be the A/C clutch wire. If it's there, then everything else will be a snack. Depending on the utes build date, the wiring for the pressure switch in the A/C gas circuit will either be up near the bonnet hinge, or down just in front of the left shocky tower. Look for two seperate spade connectors. Can't be sure of their colours though. With your Fairlane diff, make sure you get the handbrake cable with it. If you already have rear disc's, this shouldn't be a problem. Otherwise you will have to hunt down the right cable, as a drum brake one won't fit. I'm in the process of doing the similar job on my XD ute project. Also mate, I think you'll have to change the proportioning spring / valve in your brake master cylinder. There are different ones to suit disc / disc, and disc / drum brake combinations. A trip to a good brake shop might be in order..
Hope this helps!
Original XD 351 Ute - I got one!!
HSV - I just don't want one....EVER!
My XF 3 on the tree ute is ALWAYS stuck in third......