If you go to an AutoZone/O'reilly's they will look at you like you are retarded if you ask for a SPDT 30/40A relay, at least they did to me. I knew what I wanted, but without a part number or application they were lost. The one woman behind the counter was able to help me. If I didn't need it right away I would have bought one online since it's about $1.50 vs. the $7.50 I paid.