when i put in my buckets it took a drill and drill bit plasma cutter and a welder and a 30 of PBR. first off not sure what bucketts i had but they sorta fit so we positioned them in the cab, marked holes with a handy dandy sharpie and drilled holes. then since i really didnt fully trust the floor we welded 1/8" steel(with holes cut out of it) on either side of the holes and bolted 3 of the 4 down, for the 4th it took a vertical bracket(homemade) with 1 more 1/8" steel "support" on the underside of the truck
You can make anything fit. But it won't be a direct swap. With 73-96 bench seats, all you really have to do is swap tracks, or use the existing holes. IIRC, the SD seats were a little wider and makes it a tight squeeze, but I know some guys who have done it. I even know a guy who took a '03? 150 King ranch 60/40 seat and put it in his dentside. So anything can be made to work.