I had an annoying "rattle" after changing front struts on a 91 740 that was most evident a low speed when going over small bumps. Turned out to be that the "gland nut" (large nut that holds the shock in the strut tube) was not tight allowing the shock to move around inside the strut tube. Jack the front and remove the wheel. Take a long cold chisel with the point ground flat, a long drift or a large screwdriver, engage one of the "tabs" on the gland nut and use a large peeny hammer to tap it clockwise to tighten it. I though I had mine tight when I changed the strut but I was able to get a full 1 and 1/2 turns on it the second time. Stopped the rattle. I believe there is also a curved spacer in the bottom of the tube that may have come out or flipped over when the old shock was pulled out.

bl