I wouldn't touch the geerbox until I made sure the rag jont, tie rods, drag link, idler arms, and wheel bearings were all up to spec. If the box is overtightened it can break teeth when the wheel is in the center postion. Also, on R107 and w114/w115 cars the three bolts hold the box to the unibody should be torqued to spec every 30k or so, or they will come loose and make for a wandering panzerwagen.