You are buying a brand new pair of forward/backward power seat steel gear assemblies. They will replace your broken factory plastic gears. If your seat motor runs but the seat doesn't move, these are what you need. You will have to reuse your gear cases and rear thrust disc. A new front thrust washer is supplies along with hardware for reassembly.  These come with life time warranty against gear breakage.

They will work in 99-03 Ford Windstar with power seats.

The following parts are in this kit.

1 new pair of heavy steel gear assemblies
1 new pair of nylon worm drive gears
1 new pair of clevis pins with cotter pins.
2 pairs of 1/4 washers.

Detailed installation instructions provided
 
Don't forget Tribolith Grease!
 
Install Instructions