Old dodges(69 dart) had the same thing on lug nuts on one side of the car.
They tighten in use.
Pat

This topic is a sore point with me. Somewhere in my shop is the worlds
largest collection of left handed weed eater bolts. Every time I need to
change from the string head to a brush blade I have to go buy another bolt.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com