I used a starter from an E34 540i. The passenger side exhaust is in the way, so the bolts are difficult to get to. 2 17mm bolts is all it takes to remove the starter. While the exhaust is impeding to the accessibility of these bolts, it is not impossible.. I highly, recommend installing the starter prior to installing the engine/tranny in the car.
Don’t forget about starter wiring. You can do this after the engine/tranny has been dropped in the car. You will need the obvious 2 gauge power wire. You should use the one from an E34 due to the custom routing it was designed for. You can always get a 2 gauge wire from home depot or something. Make sure that the loop on the end is clamped on tight if you do the home depot route.
Now on to the other wires for routing: You will take the black wire with the yellow stripe and wire it to the starter. Remember that the starter is already grounded. You already hooked up the power. Now you need that 12V “switch”. That ignition switch wire is the black with yellow stripe and you will see on the starter, there are two tabs to attach that wire on the solenoid. Read carefully as I show you which one to mount it on. If you properly install the starter, and you look at the driver side of the engine, you will mount the wire on the spade terminal that’s on the top of the solenoid. It’s the green arrow pictured below.
No ignition coil is necessary for the swap. Each cylinder has its independent coil attached to the spark plug wire.
If you look at Figure 122, you’ll see the 3 wires highlighted. The red wire is the Starter (+) wire, going to the Power Terminal on the E30. We talked about that already. The yellow wire is the black/yellow 2.5 wire that goes to the solenoid. This has the “larger” loophole, so when you install it on the starter, you can’t mix it up with the smaller loophole. The blue “smaller” loophole is the black/green .5 wire. This is your ground redundancy wire going straight to the motor. See Figure 123 for details on the wiring.