A 5-way is not normally an OEM option on vehicles, so there is a very good chance it is not an OEM part. With the pins spread out more, that makes it even less likely to be an OEM 5-way as the plugs have not changed shape or width since 1986.
I recommend using a circuit tester like # PTW2993 to check the wiring functions. I've attached a video to assist. The 5th function will either be reverse light function that will only come on when the vehicle is shifted into reverse, or a brake... view full answer...