Saw this one on the web and is perhaps my favorite. It makes me think it could be the one I saw around 1959 at the Joliet Municipal Stadium (Quasquicentennial).
Here's the story. I wanted to build a circus style Human Cannonball truck. I was thinking about using a 54 Ford but it's just too new. Then I found a '41 Chevy pickup. PERFECT !! I figured a COE or cab over engine would look even better. So the plan is set.
After looking at all the photos on the web  I could find, like the ones on the right, I've decided on a few details to include.

1. A ladder along the top of the cannon.
2. SpotlLights on the top of the truck.
3. Budd 5 hole 20 inch wheels.
4. Some reference to Quaker products.
This list will grow.
An interesting look to this one.
Notice the support framework.
Here's the latest version you may find..
After much research and I found enough dimensions to start the project. It turns out that the grille is not usable for this project and so it goes.
Links:
Brad's '41-'46 Links
Human Cannonballs : A great source.
Time Line: Over the years
This is an earlier version of the Revell kit.