Disclamer: The following information is meant as a reference, not a tutorial. There are many steps required to properly complete a steering rack replacement/swap. These are the main tasks that were required to fit my specific application. Your needs may vary and I am not responsible for any damages or losses you may encounter.
My Car is a 1991 318iC and I swapped in an E46 M3 steering Rack (Green Tag).

Beyond fitment, its not well documented in one place about what actually needs to be modified with regard to an e46 rack in an airbag equipped car.
Here are the 5 major tasks that needed to be done to get mine to fit:
1. Spacers on top of the rack.
2. E36 tie rod ends with E46 inners to maintain venting.
3. Steering shaft can be adjusted in the car to compensate for length. Airbag cars have a 2 section shaft.
4. Firewall needs to be modified due to increased shaft angle.
5. U-joint may need to be filed to prevent binding.
The best resources I found:
See post by Kim Burgess, and following response by Greg
Write up on modifying firewall for Airbag cars good pics. It is written for E36 Rack Swap but same rules apply to E46 racks.
Sent from my MI 4LTE using Tapatalk
My Car is a 1991 318iC and I swapped in an E46 M3 steering Rack (Green Tag).

Beyond fitment, its not well documented in one place about what actually needs to be modified with regard to an e46 rack in an airbag equipped car.
Here are the 5 major tasks that needed to be done to get mine to fit:
1. Spacers on top of the rack.
2. E36 tie rod ends with E46 inners to maintain venting.
3. Steering shaft can be adjusted in the car to compensate for length. Airbag cars have a 2 section shaft.
4. Firewall needs to be modified due to increased shaft angle.
5. U-joint may need to be filed to prevent binding.
The best resources I found:
See post by Kim Burgess, and following response by Greg
Write up on modifying firewall for Airbag cars good pics. It is written for E36 Rack Swap but same rules apply to E46 racks.
Sent from my MI 4LTE using Tapatalk