Hay Hurcules, I had the same locking tab on my 1972 CL350. I have no idea why it's there. In my opinion it serves no purpose. The locking tab is formed to be placed on the torque arm #7 but as you have found out there is no way to properly place it on the torque arm because the swing arm bracket is in the way. Mine had the 2 locking tabs bent on the bolt head but with no way to connect the other part of the locking tab to something fixed it would spin when I tried to remove the nut from the other side of the shoulder-bolt. I removed the locking tab, but some locktite on the nut and installed the cotter pin. Seems to work just fine.