I don’t believe a K3 has the same bolt up pattern as the KE engines. Iseki redesigned the transmissions when the K3 engines came along. That’s all I know. Since this subject comes up on occasion I ought to look since I have both and I should be able to tell by looking at them. Keep in mind the K3 is much longer so there is more to it than just transmission bolt-up. Hydraulic lines, fuel lever linkage, wiring, frame structure, etc. would all require verification and likely modification. Finding a K3D or E might not be easy either. The driveline components are also not designed for the extra torque so life expectancy will likely be significantly reduced. Everybody likes to have more power but there are a lot of advantages by not having it such as less broken parts and longevity.