Otto, I believe it's a "core charge" like a battery. You either give them a core or get charged. I can not remember the amount. I kept my original starter and had a local guy rebuild it a year later.
I looked up NAPA shows $17.50 for a core charge and about $83.00 for Starter ( check your local store). I would bring old one with you and match it size, teeth, ect on the counter. Good luck! This starter is for 1950 6 volt 3100 216 truck:
