The plug with contacts shaped like a T plugs into your radiator support. You should have a mating plug in a hole there that passes through the signal to your front parking light/turn signal.
The plug with the light bulb in it fits in the side marker light.
I had an alternator pulley that looks very similar to that one in your picture. When the belt is thick and stands above the groove a little bit like that, it will cause the belt to wear down and become thinner, and I found it causes the belt to lose strength and traction and will chirp and squeal. I bought a deep groove pulley from an eBay seller and that solved the problem. I thought you might like to know. I can't tell for sure from your picture, but it looks from here like the belt is thicker than the groove is deep/wide. Here is the one I bought.
https://www.ebay.com/itm/201649847243
And here is the discussion about the belts and my pulley swap.
http://www.67-72chevytrucks.com/vboa...d.php?t=797722