My ford truck has a quick diagram on the face plate of the 7-way connector that shows what is on each of the 7 connections on the truck side. compare that against the color codes.
I have always had good luck with reading up on all of this from ETRAILER.COM on-line.
If you still have the original wired plug seems like you should be able to see which each color wire comes from from each of the 7-way connections. Then compare that to photos and pictorials from etrailer.com on which one to purchase.
If you have the correct cable it is very easy to change out color for color in the trailer cable junction box on the trailer side.
Roy Ken