Abit of a typo correction mate.
These is a F5C56A not a FS5C56A.

Quote from tech wiki,
Quote:

So 56A got improvements and slightly wider gears than the 56L gearboxes.
What you won't read on tech wiki is that these gearbox actually has wider and larger gears than the F4W56A gearboxes.The one i did a comparison to was the late F4W56A off a 1984 ute.

These is the only A-series gearbox that uses the Porsche patented synchromesh system.
So if you open up your 56A 5 speed and it doesn't have these synchromesh system, you don't have a 56A 5 Speed Nismo close ratio gearbox. You have a F5W56A Gx5 5 speed gearbox. And while they might share the same gearbox casings, internally, they are very different.

i.e Note the gear and gear tooth design and "how it sits on top of the steel rings" as opposed to normal gearbox with warner synchromesh rings.Also when the gear in these gearbox is fully engaged,the synchro hub doesn't go "completely over the gear engagement teeth due to the step". I will try and get the comparo pics i took.might explain better than my grammar lol

Also unlike the 60A series 4 speed and 5 speed gearboxes, gears 1-4 are not the same when it comes to 56A series 4speeds and F5C56A 5 speeds.