1957 chevrolet 4 barrel intakes early 3731398 and late 3746829

[nomad]

I have been trying to find a good correct date coded original 4 barrel intake manifold for my 1957 Chevrolet . The front assemble stamp date is F8I3F this breaks down to F= Flint Assemble plant, 8= August, 13th, and F= 283 2barrel w/ Power-glide.All cast numbered parts should be 1to 10 days prior to this assembly date. Since I am upgrading to a stock 4 barrel set up, I have noticed that all stock 4 barrel intakes that I have seen with a cast date as late as G267 or July26th 1957 have the part number 3731398 and I have seen one with a casting date of H87 or August ,8th 1957 This one has a part number of 3746829 and I guess was only used for the last month of production for 1957. Page 683 of the Danchuk parts catalog confirms this. This intake manifold part number 3746829 was used right into 1959 so it dose get confusing .