It goes in. Years ago we were putting a ca in a 240 for a customer. We got a ca18 long block for $500 and rather then spend 300 for a ca tranny, we went serching for a tranny from a ca18e s12 at junk yards. Found one local, but the transmission was very short and had a shift linkage like a Z32 300zx. We looked at the bell housing and it was identical to the ca18det bolt pattern. So we put two and two together, and only bought the bell housing rather than the tranny for $50. We had 2-3 ka trannies back at the house. So we swapped the bellhousings as you do sr/ca bell housings on ka trannies. Everthing went perfect, and we saved $250. So long story short, guessing you have a v6 s12, get a usdm s12 Ca18e tranny, with both s12 ca18e engine mounts, and it should drop in like stock. Going ka, I would assume you would need to swap a ka tranny bell housing on a ca18e transmission. Then use the stock s12 ca18e tranny mount, and I would guess you would need custom engine mounts for the ka. Either way, if I was in you shoes, I'd go ca, but thats just me, so good luck with your project to which ever swap you choose.