Honestly, the thermostat housing bolts was my first guess as they looked very familiar, but when I did an internet search for "thermostat housing bolt + 4.6" I got pics of a different type of bolt so I thought I could be wrong. The only thing throwing me off is the washer and nut on the bolt itself. I don't think the t-stat housing had any additional bolts/washers. Perhaps the bolt and washer are on these bolts by mistake?