The indented head bolts also have a built-in washer, which helps to keep the hex head from digging into the sheet metal. I don't know about higher strength. See the attached pic of bolts from Mar-K.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
