Mike,

I measured the metal thickness using a dial caliper that measures to the nearest 0.001 of an inch. A micrometer would be better, but it is an item I do not have. For "in the field" measurement, I carry a simple little "go no-go" metal thickness gage. The one I have is made by Hobart, but there are others. I use an old reference book for thickness/gage equivalences, but there are some on line like the random one I found below.

http://www.sheetmetalguy.com/sheet_metal_gauge_chart.htm

Good luck hunting, it is almost as much fun as hunting old Chevy parts!

Paul



1941 Chevy 1 1/2-ton WW2 4x4 dump truck
In the Stovebolt Gallery
Lots more pictures