My interior, including the kick panels, are still out of my '67. So I took a look under my dash.
Sorry to tell you this, but your "what is this for" connector is connected to my rear lighting harness. The corresponding male connector is 2 rows, white in color, and has the matching nib in the middle of one side.
See for yourself:
I still stand by your "rear light harness" being the bulkhead connector for the front light harness. I got a broken spare up in the attic that I could photograph if necessary. It's an image I know well due to me breaking my 1st brand new harness at the upper tab of the connector - a $150 "oops".
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
