each tranny would have its “slight difference” as in the KA has a 4th/5th gear sensor and the SR’s do not. but in the end all can be used (minus bellhousings) and gears are interchangeable so you could change ratio’s if you wanted too. but everything else is the same.
as for gearing… i dont know if a sohc/dohc KA share the same… but the DE has the same gearing as a SR, the S14 in japan @ a point had a n/a SR which had different gearing thou. then course the S15 SR has totally different gearing. a CA is geared a bit different.
This includes CA/KA/SR some VG (others used the T5) older RBs
Only the old Nissan trannies - CA (<85) L20-24-26-28, FJ, etc use the FS5W71B which uses a different shifter and countershaft bearing. They also have steel synchros. The cup for the driveshaft is also different.
There’s long and short boxes (200sx vs 240sx vs 300zx) but internally they are all the same.
I’ve swapped bellhousings on all with no problems, and you can interchange between old/new as long as you swap the countershaft bearing.
Some cars you have to lower the tranny to reach the front two bolts on the shifter plate.
I needa quick release hub for my momo wheel Varun. Ill talk to you tomm when you get back from your trip and grab my two bars as well. Take it ez
-Devin