hey guys, i was wondering if anyone might know the difference in the 1000 sedan gearbox to the 1200 sunny sedan gearbox. Are they the same ratio, are they the same size? can i use parts from one for the other? Please help

You could be in trouble the wiki says this.

"Note that the 4-speed transmission was redesigned in April 1973. Gearsets are not interchangable between early and late transmissions."

http://wiki.datsun1200.com/index.php/Transmission_Overview

The floorspeed transmission used in all 1000's & most 1200's are the 56 series. The redesigned one is the 56A.

Now just because the 1000 & 1200 used the same transmission identification code it doesn't mean that they ar the same gearbox.
They used completely different clutch actuating mechanisms in the RHD versions, so the integral belhousing part of the gearbox case is different.

As for the gears themselves, well my Gregories manual for the 1000 & 1200 lists only one set of ratios, so it would seem that with the exception of the gearbox case itself, the two are interchangeable. Gear levers are different too, but only the shape of top part, so use the lever that goes with the car.

The 56A series gearbox looks the same as the 56 series at first glance but has the characters 56A cast into the side of the case.

thanks for the help guys.