In my opinion this type of stress crack is very common in the ADs. All the trucks I've owned have had the column mount cracks under the gauges. I think the suggestions given above are plausible reasons for the stresses. It does surprise me Dave that you have been fortunate enough to get trucks that dont have this damage. Maybe these rusty Canadian trucks I'm getting are the problem wink

1970 Chevrolet C10
Grandpa's -- My first truck -- In progress to shiny
Follow the build in the Project Journal
1950 Chevrolet 1-Ton Dually
"Ole Red Girl"
In the Stovebolt Gallery
More pictures here
1951 GMC 9430 1 ton dually--Shiny! | 1972 Chevrolet C20- Rusty- the puzzle box lid for the C10 | 1962 AMC Rambler American- my wife's
Parts trucks-
1951 GMC 9300 | 1951-GMC 9430 | 1951- Chevrolet 1300