heads are perfectly round...like a flat button. i was able to get the nuts loose by grabbing the round head with the vise grips. hadn't encountered a fastener like this and was looking for some OEM info on them. when they assembled the truck they had to hold them somehow to tighten the nuts??? just wondering how they did it and what they used.....then and now???

"it's only old if you can't find a use for it; otherwise it's cool and i'll use it."