Point of order ... not all 400Fs have 6 "cabin" seats.
Max occupancy on the 400F is 8, so some deem 4 cockpit seats & 4 "cabin" seats as being sufficient. (ie why have 10 seats when you can't put 10 backsides in them...)
Edit: The 742F ladder does not have pallets either side. It comes down adjacent to position B or (2 if you prefer) and just in front of position CL (3L etc). There are other systems of position designators.