While we are on the subject, I am guessing the reason why the clutches are "different" is because of the flywheel, correct? Since the trannies are the same, just with different bell housings, that would mean that the reason why they aren't interchangeable is because of the flywheel. I am guessing if you mount a SR flywheel on your KA you can use an SR clutch. I would guess the same is true for SR owners who put a KA flywheel on their SR, they would need to use a KA clutch. :12dunno
It would be cool to find out, especially since shops like to charge more for SR parts. It's kind of like how they charge more for SR radiator hoses, especially for the top one. You can use the hose from a 1988 Mazda 323. They are the SAME hose, just one is A LOT cheaper.