We use either a BMW 2002 or 320i brake booster for this project. The 320i is the easier choice, since the booster rod does not need excessive modification. Since the 320i booster comes with a longer rod than the e30, it only requires cutting the rod to the proper e30 length, then rethreading it. The disadvantage of the 320 booster is that it gives very little clearance between brake booster and intake manifold.
The 2002 booster, while giving better clearance, requires more modification. The 2002 booster’s U-end must be cut off, then the proper length of e30 rod must be welded to the 2002 rod. This 2002 booster modification is NOT recommended for shade-tree mechanics; it requires good knowledge of the correct line-up on rod and, very important, good welding technique.
Pictures below show a 2002 booster before modification (left) and after modification (right).