What is the little black pluggy box that came out of my van??? It's not a fuse box....?

I inherited my dad's van when he died, essentially. He had left it to my sister, and it had some problems, so after her non-mechanically-inclined husband tried to fix it, she gave it to me. He pulled out this box, approximately 3 or 4 inches long, 1 inch deep, and 3 1/2 inches wide. It has plugs like the prongs on a plug you plug into the wall on one end, but they are in two horizontal lines - 5 in one, two in the other row. She said it came from underneath the dash on the driver's side, but I can't figure out where it goes. I drive a 1990 Chevy Astro (or would, if I could finish rembling things!). Thanks in advance!