Rohan, hi, saw an early M535i last night and the MC looked very similar but as I wasn't looking at that specifically would not want to bet too heavily! However, it was an excellent car, well looked after and very desirable but not for sale.
I had a manual steering box put on my car 15 or so years ago, I don't know where it was sourced but came with the lower steering column. That box was shot and last year I replaced it with a box from W&N and we then discovered the mismatch with the splines. Our guess is that the earlier manual box came from an early CS and pre-fine splines. As my original lower column had "disappeared" the solution became a made up joint with coarse and fine splines at opposite ends - more expense! Hey ho, others please take note and beware. Tim T