This thread...
http://67-72chevytrucks.com/vboard/s...d.php?t=743074
...has a picture of the connector at the cig lighter. It is the only connector like it on our trucks that I know of.
The one on the left reminds me of the wire that plugs into the "CIG" terminal at the fuse box. It should plug into that terminal at the "Y" end (left connector at the "Y" in the photo). If the one in the right has that connector for the lighter, then I think the opposite end connects to the short leg of the "Y". It's been to long since I rewired my truck to be 100% positive. If the one on the left has the funky connector for the lighter then the one on the right should plug into the short leg of the "Y" and powers the blower relay.