Gamma Globulin is a blood product. Blood and blood products were not screened for Hepatitis C or HIV until the early 1990s. Therefore Gamma Globulin, as well as other blood products, could have been contaminated with Hep C, Hep B, HIV, or any virus that was spread by blood.
I contracted Hepatitis C from a Gamma Globulin injection in the mid 1970s. Many people on the forum contracted Hep C from blood transfusions or blood products before blood and blood products were routinely screened.
You should definitely get tested for Hep C, Hep, B, and HIV to be sure you do not have any of them.
Do you have Hepatitis C? If not you may want to get tested. You are a baby boomer and its recommended you test for Hep C.