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here for further Details. Normaly there shouldn´t be any problems...
If you change the engine, you have to change the ECU too. Also the RPM-Coding.
And i think you also have to change the transmission because the connection flange is different, but i don´t know it exactly. Looooong time ago i had a E28 Diesel and i replaced the engine with the same one that was built some moths later. I got in trouble... because of the connection flange. So know what you are doing...
But a BMW is not a GM-Car, where all parts could be mixed however you want!