The 7 pin trailer hitch plugs really didn't become a factory standard until into the 2005 and newer range.

I am in need of pics from someone with the factory trailer wiring intact on their dually to post up some pics of the connections. None of the plugs I have match what I'm trying to add. I'll post pics shortly of the conundrum. I have confirmed multiple times that this is intended for my truck.

I'm trying to add a Curt 56071

My truck plugs

The 7 pin trailer hitch plugs really didn't become a factory standard until into the 2005 and newer range.

The late 90s stuff often had to have the trailer hitch wiring with the pig tails that connected to the tail light plugs on each side. At that time, the flat 4 trailer plugs were still the factory standard. Those older plug into each taillight plug harnesses went away as the factory started equipping more trucks with the 7 pin plugs, after 2005 or later. Any of those harnesses still around are very old, I'm not sure I would trust them at this point. The plugs for the taillights were pretty sketchy way back then.

If you want to put a 7 pin plug on your 97 truck, you probably are going to have to do it the old fashioned way, wire it in yourself, or hire someone to wire it in for you.