An electric puller fan with its shroud from the later E36 318i/is/ti is a direct bolt-up. I got one from a partout on another BMW forum. I also removed my aux pusher fan. Then I made a harness to run the new fan power from the aux fan plug behind the driver's side headlight to the fan (its plug is on the shroud). Cools fine and the AC still works fine although a mod'ed the wiring under the fuse panel so that the fan goes to high speed whenever I turn the AC on.
I've got the whole assembly from a Volvo which is a popular swap. Bought it from a Volvo friend but I'll never get around to installing it. Interested?