I'm by no means an expert, but I scored a KDS15 several years back for my retro kitchen remodel and I couldn't be happier with its functionality, dependability, and styling!
Up to that point, most dishwashers did have the timer below as they tended to be bulky. I think GE, Frigidaire and possibly Whirlpool were among the first to use a slimmer designed timer that would fit in the door. The more deluxe models with multiple cycle options continued with the timer in the lower compartment well into the 70's.