The early one barrel 32/33 was a single plane. late 33 up to 53 Dual plane. The first dual plane intakes (Camel backs) looked like a single plane as they didn't have any external port shaped. You could hollow them out to make a good stockcar intake.
Gramps
Single plane, both barrels of the carb feed all cylinders. Duel plane has a divider in the manifold so that one barrel of the carb feeds 4 cylinders and the other barrel feeds the other cylinders
