You mean you don't have the part to mount the cartridge to, this is the headshell. I have one from a Thorens TD160 arm I'm no longer using. I'm willing to sell, don't have a clue about price off the top of my head. Email me if interested.
If the part you are missing is on the back of the arm,Near where it pivots,I think it's The anti-skate device.There should be two small notched arms (one one either side of the armtube) facing backwards.A small weight on a line is attached to one and hangs over the other.