There are numerous places around Perth that can build/repair/modify driveshafts - and I presume the same wherever you are. Just search google/yellowpages/etc for driveshaft or driveline of something like that.
Yeah mate, most drive shaft / diff specialist can replace slip joints lengthen and shorten, balance shafts. too bad you sold that one to me. I had it lengthened and balanced.
Cost $400. Is it front or rear you need?