You'll probably have to drill 1 or 2 holes. I've done this swap a few times and the holes depend on year model.
Do beware you'll need a seat from another extended cab truck; the center brackets are different because the floor shape is unique to an extended cab.
I seat-swapped my '94 C2500LD extended cab to a 60/40 bench because the buckets it came with were ragged, bad. I had to drill 2 holes; the rest were there. You may note if you pull up the carpet on the passenger side often there are 2 forward bolt holes for the passenger side track; 1 will be plugged with a large torx bolt and you simply move it over to use the correct hole.
Be sure to get the seatbelt buckles too.
Richard