I was kind of hoping that this might be stickied somewhere, but apparently it is not.
 
Well, I got my gearbox replaced 1500kms ago. It was reconditioned by a gearbox recon company my mechanic had used for years. Got it back and second gear was a little troublesome on the downchange. It needed under 2.5k revs to do a gear change. Was informed it "might be the synchro's wearing in" as it had apparently been totaly stripped, blued and bedded in addition to the 1st/2nd strengthened. Sure, ok. did 1000kms in it. changed the oil to a 75/90. Still no improvement. Went back to the mechanic and said its not right and needs to come out agian, maybe return it to the gearbox dude. Here is the kicker, the gearbox company shut down. Yup I got a lemon gearbox now. 
 
So back to the question segment. In short form, what gearboxes suit what?
 
I have a Rev1 3sgte engine, gearbox is a "i dont know" with LSD.
 
Where are the gearbox models identified?
 
What different versions came out? (normal, LSD, Bathurst, model numbers)
 
Do they all fir to any 3sgte? (or do they have different stud fittings, if so how do identify the engine to gearbox)
 
What is the best?
 
Are there any alternative ones? (eg a supra swapout (i know this is impossible))
 
Armed with  this information and hopefully stickied to the thread, it should be informative.
 

The S, E or A series gearboxes used in the SW20 will fit any model.  The biggest differences are weight, gear/diff ratios and sheer size of the things :) 
 
Unfortunately, you don't have a whole lot of options for other gearbox swaps because more often than not, the shifter linkages are backwards - designed for FWD cars.  You can overcome this issue, buy switching the mechanisms over and modifying the casing, but unless you are okay with pulling a gearbox down, I wouldn't try it.
 
For a turbo application, the E153-734/5 boxes are immensely strong.  People across the world are feeding 500HP+ through them daily with no issues (Look up Jeff Fazio's car 'Jekel' online) however they suffer from weak 1st/2nd synchro rings and can be costly to replace.  The Boxes are also far heavier and larger than the S54 found in the NA cars.

Good info! Just need to find one......

1st series E153's had different synchros to the 93+ cars. but they are completely interchangeable. 1st series synchros suck on 1st and second gear.
 
HOWEVER, non-lsd to lsd requires different axle stubs. from memory it was about $400 new from toyota.

As mentioned the gearboxes are all interchangeable, but you need the driveshafts axels and mounts to suit.

S boxrs are suited to na, short ratios weaker gearsets thinner driveshafts.

e boxes are for turbos, long ratios beefy gearsets. Physically larger.

They improved the syncros for earlier e boxes, so when you buy new ones from toyota they should last better than the original set.

We've got two available e153 gearboxes. $800 each. Let me know if you're keen.

Hit me up with some details delivered to brisvegas

What gen is your car? if you have an early model, I have a complete box with shifter pedals driftshafts etc for $1149
 
http://www.gorillaindustr...20-mr2-e153-gearbox-2/
 
Shipping to Brisvegas is quite deadly though, $400 unless you have a forklift on your side?
 
If you don't want the full kit and kaboodle, we have a plain box for $849, but since I said $800 earlier can do for $800. Same shipping cost though.
 
http://www.gorillaindustr...sw20-mr2-e153-gearbox/

I assume it would be about the same to Melbourne as well?

Yeah pretty much, unless you have a forklift and can take the pallet off on your side without a tail lift truck. then you save about $100.