So there are 3 main variants of the KA and it's VERY important that you're a bit more specific about what it is you're looking for exactly;
The Altima had a FWD variant of the KA24DE.
Nissan pickups had a variant of the KA24DE that was built in Mexico I believe.
240sx's, S13 and S14, had Japanese made KA24DEs.
Little background on the KA engine, the wiki has it pretty well summed up.
https://en.wikipedia.org/wiki/Nissan_KA_engine
https://www.ebay.com/sch/i.html?_from=R ... E&_sacat=0
They come up sometimes in a few facebook groups but I would almost never buy one sight unseen from an individual on the internet.
https://www.facebook.com/groups/Driftin ... 5686814899
Or try a salvage yard. This site works pretty well, it's where I found my Z32 transmission.
https://www.car-part.com/