I completed this swap about a month ago and wanted to let y'all know of some of the issues I ran across in case anyone else wants to try this.
The donor seats were from a 2003 hardtop GT...full power leather seats.
The seats being replaced were 1994 leather in a vert GT...full power
I had hoped that this would be a simple bolt-in job. No such luck but not an impossible task. Fortunately the rails and all controls were included with the seats.
Passenger side - The mounting rails are completly different. If your old seat track is worn out, make sure you can get one to match the one that comes out. Fortunately the seat pan mounting holes are identical in the old and new seats. In order to do the swap you have to take the rails from the old seat and mount on the new seat. Beware of the tension on the springs when removing the pan bolts...spring loaded seat tracks can do some pretty good soft-tissue damage if you are not paying attention to what you are doing.The new seat will bolt right in after the rail swap...easy as pie.
Drivers side - The power seats are a completely new design from 1994 to 2003. LUCKILY on the drivers side, the seat track rails on the 2003 seat match up with the holes in the 1994 floor pan. The electronics are a completely different story. The 1994 power seat has a two-wire plug. The 2003 seats have a 4 wire plug due to the fact that the seatbelt is attached to the seat. You will need to strip the old connector ends, match the larger wires(Large ones are the power supply, small ones are 2003 seatbelt wiring)...black to black, blue to blue for the power seat...and connect with a new connector which is eay as strippin the wire ends and clipping on a new connector. BE SURE to not let the ends of the wires touch during this process...or better yet, make sure you have a few replacement fuses on hand. I think they are the 6 amp green ones under the hood. The book has a diagram that I had to reference. I blew two 'high-voltage' fuses under the hood during the process. The two smaller wires on the 2003 seat can be sealed off with electrical tape as they are seat belt related.
The seat belt mounts are no real problem. 1994 mounts are on the floor pan. 2003 are on the seats. Removing the 2003 mounts is easy...one bolt and they are off so that you can use the original floor mounted seatbelt setup. As mentioed, seal off the wires on the new 2003 drivers seat.
Drawbacks...2003 seat has no lumbar control...1994 did, and I loved it for long drives. 2003 design is slightly different. The 'bucket' seating is not quite as much of a 'bucket' and lateral support is less...that is more of a preference decision.
Positive...headrest looks better that the old 1994 fat one IMO. Pony stitching looks good. 2003 drivers seat has seat tilt control options...1994 did not have tilt, only up/down, back/forward. And most importantly, no big-ass holes from 9 years of wear and tear.
I have no idea what year Ford changed the seat design...but I'm sure I'm not the only person to say' "Oh S&!%" at first look when they had a look at the underside of a SN95 drivers seat side-by-side with a newer power seat. The difference is like looking under the hood of a pre-electronic controlled engine versus a new Cobra.
Y'all have fun!
;-)
Seat Swap '2003 to '94 
And it was the faux part on the side that finally gave up the ghost.
