Just measured my existing ’03 - 60/40 Seat Pan Mounting Holes, the same for the Buckets in that time frame.
Side to Side: 11 3/16” as close as an eye ball can get.
Back to Front: 13” again the eye ball.
Take some time and disassemble the passenger’s Seat or see if you can measure up the Mounting Holes in the “SEat Pan” and see if you can switch just the Seat not the Frames.
The "Seat Pan" - is the part that the Cushions and Upholstery attaches to and on my ‘03s the Slider/Frame can be unbolted from.
4x4, 5sp, Std Cab, Stepside, E4 Red
4” Lift - Coil-Overs, 6” SkyJacker Leafs - No Blocks (Mistake)
31 Spline FX4 Rear Axle, 4.56s and OX Locker, Hurst Shifter w/Optional Stick and "Made by Grev" alignment adapter