A stylus isn't generally going to hold up well after 30 years. You're better off with a new one. Assuming you mean you have the ADC XLM 100, you could perhaps find a replacement here:

http://www.turntableneedles.com/ADC_c_24991.html

But besides that, cartridges are mostly interchangeable, with a few exceptions here and there. You can get something else besides the ADC replacement.