My '46 2 ton has that booster looking thing on the right frame rail.. right in the neighborhood of where the "spicket" for the gas tank sticks out.

It was my understanding that it was some sort of vac assist to the brake system, but I really don't know for sure.. I just put fluid in the master cylinder, bled the brakes, and let sleeping dogs lie.

an idea is only stupid if you think about it rationally.