Have you ever SEEN one IN PERSON that had 318 size ports? I've not. That doesn't mean anything, but I've never in my life seen one and I've pull a good many off in junkyards. Always had the 340/360 port size. I've seen some the casting number decoded to "318" but they still had the large port size.
I have seen only 2. Came factory on a 78/79 1/2 ton. I did measure the ports which were the small ports. That was in the late 80s or early 90s. Haven’t seen any since. Kim
