Hi Jason!
I have a spec booklet for 1946 trucks that give dimensions for, what I think you're looking for. I scanned the page but it doesn't come out so that you can see the numbers. At any rate, if you contacted the GM Vintage dept. and asked for a 'spec' booklet for 1946 I think you'd find it useful. They do charge for them though.
Good luck with the project.
George
