Yes, it’s aftermarket. It ties into the factory one down by the frame rail. Do you have have a picture of this black wire ? Should it run from 1 of the 3 electrical connectors on the firewall, beside the power booster ? Id like to see what that factory terminal looks like at the end of the black wire. Was it a spade or was it round ? I looked and couldn’t find anything. ThanksLooks like an aftermarket proportioning valve - factory is mounted lower, by the frame rail. You're looking for one black wire.