I saw that one too before I started on mine so I had an empty case bolted to a bare magnum block that I was using for mockups. Cut off the ears and still had clearance problems. The main problem is that the tailshaft is much larger on the 518 than the original 904 that was in the car and its the tailshaft part that goes thru the upper and lower part of the crossmember. Plus you need to open the floor up a little to clear the VSS or speedo cable. Its really close in that area. Naturally once you open up the top of the crossmember, the floor needs to be reshaped to fit. Then the rear portion (behind the crossmember) needs to be formed back into the original floor. Naturally the crossmember is where the torqe from the torsion bars is applied so it needs to be solid enough to resist flexing when you go over bumps, etc., that put stress on the t-bars. If someone was going with a totally different front suspension, such as the Alterkation unit, then the crossmember could probably be just cut out and not replaced on the top. providin sub-frame connectors were used. I suppose there are a lot of ways to do it. Mine was just one of them.