V6 SW20 gearbox choices.

Hey Guys!
I've recently purchased a project car that is need of a new gearbox. The car is a 1991 model Japanese import that has been converted from a 3sge to a 1MZ-fe. The gearbox had blown a couple months ago and is beyond the point of repair. I'm ineterested in upgrading to a turbo spec gearbox that is capable of withstanding the punishment of the V6. After doing some research I've been told that there are several variations of the E153 box. I'd be interested in getting a later model one with low km's and an LSD. I only plan on swapping the gearbox once so I think it is worth getting the best. I have a Fidenza alloy fly wheel and aftermarket clutch (not sure which brand or model). I know I will need LSD shafts, but some people have said the gearbox will need longer bolts to attach to the engine as well as a different shifter linkages. I'm not sure if those last two are correct. So please share any knowledge you have, it will be greatly appreciated.
If there is anything you think I've missed, need to know or should know please let me know.

My questions are:

1, how rare is the gearbox I'm after?

2, What years did the box come in? Incase I decide to import one?

3, appart from just the gearbox what other parts will I need to fit this to my current setup?

4, will the engine need to be dropped to do the swap, or make life a lot easier to do so?

5, are there any alternatives?

6, is it possible to put an LSD in a non LSD E153 box? If so how hard and how much?

I've enquired about his gear box and it's a little beyond my budget. He wanted $2,200 for just the box and $500 for hubs. He also doesn't have the LSD drive shafts. I'd want to try purchase it all together to save time and see if I could get a better deal.

Thank you though.

Few answers to your questions. (maybe wrong but from my experience)
 
1, how rare is the gearbox I'm after?  Late model gen 3 in good working condition - fairly rare + expensive if you find one.

2, What years did the box come in? Incase I decide to import one?  late 1993 - 1998. 

3, appart from just the gearbox what other parts will I need to fit this to my current setup?  Turbo drive shaft axles + a few other little bits.

4, will the engine need to be dropped to do the swap, or make life a lot easier to do so?  No, can be done with engine in.  (bout a 2hr job - one way)

5, are there any alternatives?  Not sure

6, is it possible to put an LSD in a non LSD E153 box? If so how hard and how much?  Not sure
 
Hope this info helps.