Hi Matt
There is place in bankstown called The Gearbox Factory 97902984. They have been building gearboxes for over 30 years and are very good. It will cost you around $1200 plus $650 r&r to replace all syncro's, seals and bearings.
I had to replace my gearbox because the gears were burnt. So I bought a brand new gearbox from Just Jap for $3200, which is a 1998 spec gearbox from nissan.
Not cheap, but atleast it will be complete.
Hope this helps
Cheers
Nick