I think the linkages and motor are just underneath the cowling - no need to go under the dash. It's been many years since I worked on one though so could be off here. Remove the wiper arms and hubs from the posts. Look carefully at the cowling - it is usually 2 pieces. One piece has to come up first as it will overlap the other in the middle. Some Fords have a small screw in the piece that has to come off first. Then they are held with clips you can pry up. Let us know if that works and what you find out.