If I remember correctly, you just need to cut the 2 prong connector off the old seat and splice it in to the power and ground of the new seat harness.
I am pretty sure two of the 4 prong connector's wires are for the seatbelt. I'm sure a simple google search can differentiate which wire is which, otherwise you can figure it out with a multimeter
- 1998 Mustang GT Convertible: 5-Speed, 2001 PI 2V swap, o/r h-pipe, Magnaflow catback, MGW shifter,
3.73 gears, Auburn LSD, TA diff cover, MM FLSFCs, Ford Strut Tower Brace, J&M SS Brake Lines, and a lot of visual/restoration work.