I'm not sure which dimensions you're talking about, but in terms of bed size the F-150 has been very consistent over the years (although I think Crew Cabs — although they always existed — have become more popular). The Ranger still cannot fit a full sized sheet of plywood flat in the bed.
Quick research: the new Ranger's bed size has only increased 0.9" (width) relative to the 1990 version. Bed length seems to be the same.
Quick research: the new Ranger's bed size has only increased 0.9" (width) relative to the 1990 version. Bed length seems to be the same.