My 2 cents, don't waste your time trying to do what I tried, bought an old eta and between my old one and one from a 1994 320e i tried to rewire it.
Did the complete process twice and both times the car stumble once you pressed the gas. I wired and rechecked my wires 20 times and both times it failed.
Wasted a lot of hours but it was interesting for me. spend 1500 and buy one.
very easy to install if you have the right tools, also the connector is ruine after you remove the wires.