X2 on the stamp. Front center or back corner (by the connector)
That metra is a repair plug. It has female connectors. Walmart normally just has the male connectors (what you would plug into the factory connector)
I *think* this is the correct pin:
http://67-72chevytrucks.com/vboard/s...2&postcount=13
That labels orange as memory..essentially 12v constant.