Amateur Radio
First issued 1956
pairs 1956-1974
Plate serial is owners FCC ID.
South Carolina is in Call Area 4 (Alabama, Florida, Georgia, Kentucky, North Carolina, South Carolina, Tennessee, Virginia). I believe if one relocates to SC from another region, they may keep their call sign.
FCC issued original prefix of K after WWII (K4AAA to K4ZZZ), then W prefix (W4AAA to W4ZZZ), then Wx (WA4xxx ...)
In 1976, Federal Communications Commission revised issuance categories http://wireless.fcc.gov/services/index.htm?job=call_signs_1&id=amateur