Hello, I have a D21 from 1990 with a bad engine. I brought a second-hand KA24E engine and a friend of mine is doing the engine swap. Even if the engines look the same, they are different; for example, the engine distributor of the D21 engine does not fit the new engine. I believe the engine that I brought was of a car, maybe a Nissan 240 SX. My question is, can I still use the pickup CPU and hardness, or do it will need to be changed?

Might need to swap out some things from the old engine to the new engine (such as sensors) but theoretically it should work if the truck was originally KA. I once swapped a EJ20 into a subaru that had an EJ25 originally and once I swapped the sensors, crank gears, and intake manifold from the US engine the JDM engine worked on the old ECU/Harness just fine. Albeit a little rich.