240Z gearbox question

Hello there. I am wanting to know about the gearbox known as the FS5C71A. I know it was introduced in the Roadster 2000, in about 1967. It known to have a 3 piece case with a stright stick. It had a variant, same numbers except the C was a W (FS5W71A) which had the weaker warner style brass syncros (instead of servo style steel syncros). I thought this box would be rare, but I believe it was original equipment on the 1969-1971 240Z as well? This is where I need confirmation from a "Z head" as you like to refer to yourselves!!! Is it true? I also heard that the 1972-1976 240Z had the next evolution, the FS5C71B which differed in that it had a 2 piece case and a bent stick. Had almost identical ratios, slightly different. Can someone confirm? Note that I might be out by a year in any or all of my release dates as I am in AUS not US.

Why I ask? I am wanting a period (produced in the same years) datsun 5spd gearbox to run in my race Datsun 1600 (P510 in the US). The model run for these cars in AUS was 1968-1972, so basically I need the strongest Datsun 5spd from this 68-72 period I can get. It either going to be the A or the B box, depending on what you guys say on the 2 boxes (and wether the B box was released before the end of 72 or not).

Is A better than B?

Do I have my details correct?

Are both boxes hard to find?

Is either one easier to rebuild/strenghten?

Cost?

Note that I cant run latter model boxes, ie Option 1 box, its against the regulations. Or I'd run my Opt 1 and be done with it!!

Hope someone can help.

Thanks.