One of my trucks also has the combination box with the fold down cattle racks.
The cattle part is made of 1x4's; and the spacing between them is also about 3 1/2 inches (or about the same as the width of the board).
Hope this helps.


Rich
1947 Loadmaster
1947 Chev. Loadmaster
1959 Chev. Viking 40

Life is short--eat dessert first!