I don't specifically remember seeing something like that on my 400 'vert. But you took tons of pictures of it. Can you see anything from the picts? It is a second week of Sept '67 build, so similar timeline. I am just swamped at work and homefront so its hard to get pictures of anything these days. Sorry.
I am 98% positive my red 'vert has it's born-with carb. But it is an automatic, not a 4-speed.
I used to be indecisive. Now I'm not sure. I feel like I am diagonally parked in a parallel universe. 1968 400 convertible (Scarlet) 1976 T/A - 455 LE (No Burt) 1976 T/A New baby, starting full restoration. 1968 350 - 4 speed 'vert - 400 clone (the Beast!) 1968 350 convertible - Wife's car now- 400 clone (Aleutian Blue) (Blue Angel) 2008 Durango - DD 2008 GXP - New one from NH is AWESOME! 2017 Durango Citadel - Modern is nice! HEMI is amazing! 1998 Silverado Z71 - Father-daughter project 1968 400 coupe - R/A clone (Blue Pearl) (sold) 1967 326 convertible - Sold 1980 T/A SE Bandit - Sold