need a new gearbox for my 1600, where's the best place to go (pref belco area) also suggestions to go to get the beast tuned when necesary...

try gas tune for tunning
and ring sss sydney for parts

I was lucky enough to pick up a low kay Sylvia import box from Capital Parts Plus, about two years ago for $600,(pretty good considering the Ceramic cushion clutch I put in it cost $850).
Give them ago or try a Jap parts place in Sydney.

Might wanna think about converting to a Skyline box?
(FJ parts are starting to become rare as especially in new or near new condition).Just a thought

As for tuning you can try Jakes Performance at Mitchell or Ben at IN TUNE
in Fyshwick, both are flat chat if you don't mind waiting a while but do top work.
Not much in the Belco area unless you wanna go to Dyno Tune?

Let us know how you go?