This is the type of connector GM used to factory wire accessories that plug into the "IGN" receptacles on the 78+ fuse boxes.
They plug in to the front of the fuse box. And unlike a generic male blade terminal, the connector's plastic shell has a latch to hold it securely in place.
Here's one source for them -->
http://www.repairconnector.com/gm-ig...ock-tap-clear/