I would try to check with Edelbrock to find out the correct application. This is just a guess, but the D64 makes me think it is probably for early (64-65) 273 heads. D=dual carb, 64= 1st year it fits. The reason is I think with the Dual plane manifold they used a progressive type of numbering. D4B= dual plane 4 barrel, for early 273 heads. LD4B= late dual plane 4 barrel, for late 273 & 318 heads. LD340= late dual plane 4 barrel, 340 head port size.
