Correct! The 63' is Metal and 64' is plastic. Some of these dash and a/c parts are listed as both. Although they may be interchangeable as far as fitment, they are definitely different in style and looks. Here are some pictures I have been referencing, a couple of them I have in my possession. Let's start with the dash, the 63' Dash (yellow) has an angled cutout for the vent Vs. the straight square cut on the 64' dash that I shared earlier. I included a picture of the 63' metal vent and duct. If you look closely at the duct it is completely different from the 64', the 63' duct has some pretty distinctive looking ears on the side where the vent attaches. The ebay picture is of the duct I purchased and shared in the previous reply. It was listed as 63-64, I didn't say that earlier just to spare any confusion. But it's pretty clear that it's totally different than the 63'. The other picture with the red outline is of a post on craigslist selling the complete a/c system for a 63' Impala Only. You can see that the vent and duct match the other picture of the 63 vent and duct.
So what do you think? I think that the picture I sent earlier with the two different ducts will both work with the 64' vent. The question is, why are there two different one's? I'll have to do some more research, especially since they are completely different in design. As far as the 63' goes, It seems like only the one style would work, the one that's completely different from the two 64's. Hope this helps you as well!
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