Hey 48CTD: I did something similar to my 3100. Used the 3rd seat from a mid 90s Ford Windstar ($50 brand new take out still had the plastic on it). I too cut out the original pedestal, leaving that 4" riser just forward of the gas tank (took the gas tank out of the cab too...like your 48). Anyway, the seat bottom was just not firm enough so what Idid was sandwiched a piece of 1/4" MDF between the upholstery springs at the bottom and the foam above....made a big difference! . Built my own 2 pedestals from treated 4x4s which I wrapped in the same carpet that I used on the floor. Also I made a paper template of the floor and transferred that to a sheet of 1/8" aluminum but before I bolted everything down I first filled that depression in the floor w expandable urethane foam. My entire floor is now flat, insulated and carpeted. Engineered a power seat mechanism from a 90 Park Avenue to it also. Lots of jackology but I love the bench seat, very comfortable and can seat 3 normal people easily. Hope that helps....Dave.
