I have heard that the traditional 3 carb manifolds (such as Offy) interfere with the firewall and/or fender brace in AD trucks. And looking in the engine bay, would agree that is probably true.
Here’s a goofy idea that might minimize the amount of custom fab work a guy would have to do to run three carbs in a 47-55 truck. It’s a pretty half-baked idea, feel free to shoot holes in it.
Take a 3 carb manifolds (use Offy just to picture it). Flip it upside down. Run three UPDRAFT carbs. There were at least a few updraft carbs that had an accelerator pump type of system. Trick would be finding ones the right SIZE.
It would be ugly as sin unless you did some custom milling of the exhaust heat provision which would be facing up. Clearance with a stock manifold might be a problem, too. Might force you into headers.
