On my '44 ton-and-a-half, the suction line for the booster comes off the manifold (not sure this is stock - seems like it usually comes off a thing under the carb maybe?), and goes to a small, fuel-filter shaped thing on the firewall on driver's side, then from that to the booster canister. Don't really know what that firewall doomaflitchy is - maybe a breather like he says? Don't remember seeing anything like it in Chevs of the 40s or Jim Carter's catalogs.
Not sure this helps. I'll look more closely tomorrow and post.
-Michael
