In the 2007 parts manual it's listed twice, once on the 4.7L engine wiring page and again on the 5.7L engine wiring page. Although they list the same part number on both sheets, it shows 3 connectors on the image for the 5.7L page and only 2 connectors on the 4.7L page.

In the 2006 parts manual its the same scenario with the P/N Gulf posted... except that the 5.7L engine had two other harness options.

I'm thinking in 2007 they made it a standard harness and some guys just have an extra connector hanging around. The new part number might include a cap.