I'm swapping my 56 series 4 speed gearbox with a 60 series 5 speed, which I believe is from a b310. The motor is the stock A12 on my 120y.

Should I use the B310 thrust bearing carrier (marked "B") or the one from my 120y?

You need the thrust bearing housing from the 60A g/box, as the 60 series boxe need a longer housing. If you use the standard 56a housing the throwout bearing won't touch the pressure plate fingers & the clutch wont disengage.

The one stamped "D" is best

So the carrier is determined by the choice of gearbox, as opposed to the motor? Or is it a combination?

gearbox and flywheel/clutch combo

I got the bearing carrier out of the 56 series 4 speed, and it turned out to be a few mm longer than the one supplied with my 60 series 5 speed (marked "B").

So should the use the slightly longer 56 series 4 speed one, the shorter 60 series 5 speed carrier (supposedly), or another carrier all together?

Here's my two bearing carriers. The 120y one is a few mm longer.




http://datsun1200.com/modules/myalbum/photo.php?lid=22754

It depends on whether you use the engine plate or not. It doesn't depend on the year or the gearbox.

Hiya, I had a similar prob when fitting up and a15 to a 4 speed and I hope I can help out a bit here.....It depends on what flywheel you are using as the a15 flywheel is thicker. You,ve prob got a standard a12 flywheel so use all the 4 speed stuff.
I fitted an a12 flywheel to my a15 so I could fit it to a 4 speed.....

The only thing that has changed in my setup is the gearbox.
So it sounds like I just use the carrier I was using before (The stock 120y one).
Thanks all.