RE: How to tell the difference between T-5 and a N
The T5 will have a funky looking shifter that sits about flush with the tunnel. It is weird. Also the case on the T5 will look much beefier, it will also have torx bolts holding it together. The output area is also very different, you cannot use the other driveshafts with it unless you ger the right connector for it. I would go with the NA nissan tranny if given the choice.
Although I have an '82 turbo with the T-5 and have no qualms about how it shifts, I have been told (and have read in this and other Z forums numerous times) that it feels clunky compared to the N/A 5-speed. Nissan apparently thought they'd need a beefier 5spd to go with the turbo engine, but the truth is the N/A transmissions are routinely used with much more powerful engines than the 180 claimed horses that the turbo motor cranked out. And they hold up fine. They're also cheaper and more plentiful, which is why I'd go for one of those if I were you.