Take the cable off the negative terminal first. Although less of a concern on some Corvettes, this is a good habit to develop. Otherwise, if a wrench touches a grounded part while disconnecting the positive terminal first, an out-of-control arc welder is instantly created. After the negative cable is disconnected and moved safely away, it's safe to disconnect the positive side. Use a 5/16 six-sided socket or wrench for side terminals.