Wanted - Cartridge for Sears Silvertone phonograph model 307

Hi, I'm looking for the following cartridge: Silvertone catalog # 57-8893D for needle # 57-8811D. I can't find them anywhere and this model is from the 1960's. I lost the cartridge a while back when I took it out to replace the needle. If someone could let me know where I could purchase one, or if they have any info on alternative replacement cartridges, I would be most appreciative. You can email me at: heidijean75@aol.com. Thank you.