That appears to be C102 used with options NYS or JL4. Its for the instrument panel to chassis harness. This is the pinout for it. I would be real wary of a harness that doesn't match. GM has a bad habit of using similar harnesses that are pinned different depending on the options. Plug them in and suddenly your wiper switch honks the horn or the horn switch turns on the brake lights.
Images (Click to enlarge)
Saturday, October 31st, 2020 AT 4:01 PM