Tony at Global Automatics in Bibra Lake/Spearwood is worth a try as he knows Mustangs quite well and has some good contacts. Sorry I don't know his number.
The trouble is finding the parts locally (I'm guessing you don't have them?) as there isn't much around and a number of the bits are year specific. Everything is rebuildable if you have the parts and ebay is a good starting point. Someone is selling the important ram and draglink at the moment, which are useful as they are powersteering specific. All parts are available in the US and even though its an expensive option (mainly because of freight) buying from there works out to be the same price as buying old parts in Aust and rebuilding them. Anyway, Tony should be able to help with what needs to be done.
Brad.
