Gene: Thanks for the info. I have another intake, cast number 839005, which my parts book identifies as 37-39. The vacuum port location on this one is just under the carburetor mount area rather than the rearward location on the 838398. Do you have any info on this one?
I took a good look at the cast number on the other intake to see if I misread it. The numbers are hard to read but the first number is a 3 and the last two numbers are 2's. I don't see any cast numbers in my book where the last two numbers are 2's. This manifold is attached to an exhaust manifold with a cast number of 3835587 which my book says is a 50-56 235 or 261. Does this help to identify it?