A Core deposit is a form of deposit you pay until returning your old part. If you don't have the core at the time of purchase, you must pay the core charge. That charge is refunded to you when you return the core.
Torque converter nut for various Ford applications 1964-00. When replacing torque converter nuts, it is always a good idea to replace all four. This particular nut is thread size 3/8-24" and comes in a box of four.